diff options
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 5041 |
1 files changed, 3618 insertions, 1423 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7c6414fc669..fea7d3335e1 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -26,6 +26,9 @@ #include <linux/slab.h> #include <linux/profile.h> #include <linux/interrupt.h> +#include <linux/mempolicy.h> +#include <linux/migrate.h> +#include <linux/task_work.h> #include <trace/events/sched.h> @@ -110,6 +113,24 @@ unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL; unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL; #endif +static inline void update_load_add(struct load_weight *lw, unsigned long inc) +{ + lw->weight += inc; + lw->inv_weight = 0; +} + +static inline void update_load_sub(struct load_weight *lw, unsigned long dec) +{ + lw->weight -= dec; + lw->inv_weight = 0; +} + +static inline void update_load_set(struct load_weight *lw, unsigned long w) +{ + lw->weight = w; + lw->inv_weight = 0; +} + /* * Increase the granularity value when there are more CPUs, * because with more CPUs the 'effective latency' as visible @@ -157,59 +178,61 @@ void sched_init_granularity(void) update_sysctl(); } -#if BITS_PER_LONG == 32 -# define WMULT_CONST (~0UL) -#else -# define WMULT_CONST (1UL << 32) -#endif - +#define WMULT_CONST (~0U) #define WMULT_SHIFT 32 -/* - * Shift right and round: - */ -#define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y)) +static void __update_inv_weight(struct load_weight *lw) +{ + unsigned long w; + + if (likely(lw->inv_weight)) + return; + + w = scale_load_down(lw->weight); + + if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST)) + lw->inv_weight = 1; + else if (unlikely(!w)) + lw->inv_weight = WMULT_CONST; + else + lw->inv_weight = WMULT_CONST / w; +} /* - * delta *= weight / lw + * delta_exec * weight / lw.weight + * OR + * (delta_exec * (weight * lw->inv_weight)) >> WMULT_SHIFT + * + * Either weight := NICE_0_LOAD and lw \e prio_to_wmult[], in which case + * we're guaranteed shift stays positive because inv_weight is guaranteed to + * fit 32 bits, and NICE_0_LOAD gives another 10 bits; therefore shift >= 22. + * + * Or, weight =< lw.weight (because lw.weight is the runqueue weight), thus + * weight/lw.weight <= 1, and therefore our shift will also be positive. */ -static unsigned long -calc_delta_mine(unsigned long delta_exec, unsigned long weight, - struct load_weight *lw) +static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight *lw) { - u64 tmp; + u64 fact = scale_load_down(weight); + int shift = WMULT_SHIFT; - /* - * weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched - * entities since MIN_SHARES = 2. Treat weight as 1 if less than - * 2^SCHED_LOAD_RESOLUTION. - */ - if (likely(weight > (1UL << SCHED_LOAD_RESOLUTION))) - tmp = (u64)delta_exec * scale_load_down(weight); - else - tmp = (u64)delta_exec; + __update_inv_weight(lw); - if (!lw->inv_weight) { - unsigned long w = scale_load_down(lw->weight); - - if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST)) - lw->inv_weight = 1; - else if (unlikely(!w)) - lw->inv_weight = WMULT_CONST; - else - lw->inv_weight = WMULT_CONST / w; + if (unlikely(fact >> 32)) { + while (fact >> 32) { + fact >>= 1; + shift--; + } } - /* - * Check whether we'd overflow the 64-bit multiplication: - */ - if (unlikely(tmp > WMULT_CONST)) - tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight, - WMULT_SHIFT/2); - else - tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT); + /* hint to use a 32x32->64 mul */ + fact = (u64)(u32)fact * lw->inv_weight; - return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX); + while (fact >> 32) { + fact >>= 1; + shift--; + } + + return mul_u64_u32_shr(delta_exec, fact, shift); } @@ -259,6 +282,9 @@ static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp) return grp->my_q; } +static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, + int force_update); + static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) { if (!cfs_rq->on_list) { @@ -278,6 +304,8 @@ static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq) } cfs_rq->on_list = 1; + /* We should have no load, but we need to update last_decay. */ + update_cfs_rq_blocked_load(cfs_rq, 0); } } @@ -294,13 +322,13 @@ static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list) /* Do the two (enqueued) entities belong to the same group ? */ -static inline int +static inline struct cfs_rq * is_same_group(struct sched_entity *se, struct sched_entity *pse) { if (se->cfs_rq == pse->cfs_rq) - return 1; + return se->cfs_rq; - return 0; + return NULL; } static inline struct sched_entity *parent_entity(struct sched_entity *se) @@ -308,17 +336,6 @@ static inline struct sched_entity *parent_entity(struct sched_entity *se) return se->parent; } -/* return depth at which a sched entity is present in the hierarchy */ -static inline int depth_se(struct sched_entity *se) -{ - int depth = 0; - - for_each_sched_entity(se) - depth++; - - return depth; -} - static void find_matching_se(struct sched_entity **se, struct sched_entity **pse) { @@ -332,8 +349,8 @@ find_matching_se(struct sched_entity **se, struct sched_entity **pse) */ /* First walk up until both entities are at same depth */ - se_depth = depth_se(*se); - pse_depth = depth_se(*pse); + se_depth = (*se)->depth; + pse_depth = (*pse)->depth; while (se_depth > pse_depth) { se_depth--; @@ -398,12 +415,6 @@ static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq) #define for_each_leaf_cfs_rq(rq, cfs_rq) \ for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL) -static inline int -is_same_group(struct sched_entity *se, struct sched_entity *pse) -{ - return 1; -} - static inline struct sched_entity *parent_entity(struct sched_entity *se) { return NULL; @@ -416,20 +427,20 @@ find_matching_se(struct sched_entity **se, struct sched_entity **pse) #endif /* CONFIG_FAIR_GROUP_SCHED */ -static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, - unsigned long delta_exec); +static __always_inline +void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec); /************************************************************** * Scheduling class tree data structure manipulation methods: */ -static inline u64 max_vruntime(u64 min_vruntime, u64 vruntime) +static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime) { - s64 delta = (s64)(vruntime - min_vruntime); + s64 delta = (s64)(vruntime - max_vruntime); if (delta > 0) - min_vruntime = vruntime; + max_vruntime = vruntime; - return min_vruntime; + return max_vruntime; } static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime) @@ -465,6 +476,7 @@ static void update_min_vruntime(struct cfs_rq *cfs_rq) vruntime = min_vruntime(vruntime, se->vruntime); } + /* ensure we never gain time by being placed backwards. */ cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime); #ifndef CONFIG_64BIT smp_wmb(); @@ -585,11 +597,10 @@ int sched_proc_update_handler(struct ctl_table *table, int write, /* * delta /= w */ -static inline unsigned long -calc_delta_fair(unsigned long delta, struct sched_entity *se) +static inline u64 calc_delta_fair(u64 delta, struct sched_entity *se) { if (unlikely(se->load.weight != NICE_0_LOAD)) - delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load); + delta = __calc_delta(delta, NICE_0_LOAD, &se->load); return delta; } @@ -597,7 +608,7 @@ calc_delta_fair(unsigned long delta, struct sched_entity *se) /* * The idea is to set a period in which each task runs once. * - * When there are too many tasks (sysctl_sched_nr_latency) we have to stretch + * When there are too many tasks (sched_nr_latency) we have to stretch * this period because otherwise the slices get too small. * * p = (nr <= nl) ? l : l*nr/nl @@ -638,13 +649,13 @@ static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se) update_load_add(&lw, se->load.weight); load = &lw; } - slice = calc_delta_mine(slice, se->load.weight, load); + slice = __calc_delta(slice, se->load.weight, load); } return slice; } /* - * We calculate the vruntime slice of a to be inserted task + * We calculate the vruntime slice of a to-be-inserted task. * * vs = s/w */ @@ -653,55 +664,55 @@ static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se) return calc_delta_fair(sched_slice(cfs_rq, se), se); } -static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update); -static void update_cfs_shares(struct cfs_rq *cfs_rq); - -/* - * Update the current task's runtime statistics. Skip current tasks that - * are not in our scheduling class. - */ -static inline void -__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr, - unsigned long delta_exec) -{ - unsigned long delta_exec_weighted; - - schedstat_set(curr->statistics.exec_max, - max((u64)delta_exec, curr->statistics.exec_max)); +#ifdef CONFIG_SMP +static unsigned long task_h_load(struct task_struct *p); - curr->sum_exec_runtime += delta_exec; - schedstat_add(cfs_rq, exec_clock, delta_exec); - delta_exec_weighted = calc_delta_fair(delta_exec, curr); +static inline void __update_task_entity_contrib(struct sched_entity *se); - curr->vruntime += delta_exec_weighted; - update_min_vruntime(cfs_rq); +/* Give new task start runnable values to heavy its load in infant time */ +void init_task_runnable_average(struct task_struct *p) +{ + u32 slice; -#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED - cfs_rq->load_unacc_exec_time += delta_exec; -#endif + p->se.avg.decay_count = 0; + slice = sched_slice(task_cfs_rq(p), &p->se) >> 10; + p->se.avg.runnable_avg_sum = slice; + p->se.avg.runnable_avg_period = slice; + __update_task_entity_contrib(&p->se); +} +#else +void init_task_runnable_average(struct task_struct *p) +{ } +#endif +/* + * Update the current task's runtime statistics. + */ static void update_curr(struct cfs_rq *cfs_rq) { struct sched_entity *curr = cfs_rq->curr; - u64 now = rq_of(cfs_rq)->clock_task; - unsigned long delta_exec; + u64 now = rq_clock_task(rq_of(cfs_rq)); + u64 delta_exec; if (unlikely(!curr)) return; - /* - * Get the amount of time the current task was running - * since the last time we changed load (this cannot - * overflow on 32 bits): - */ - delta_exec = (unsigned long)(now - curr->exec_start); - if (!delta_exec) + delta_exec = now - curr->exec_start; + if (unlikely((s64)delta_exec <= 0)) return; - __update_curr(cfs_rq, curr, delta_exec); curr->exec_start = now; + schedstat_set(curr->statistics.exec_max, + max(delta_exec, curr->statistics.exec_max)); + + curr->sum_exec_runtime += delta_exec; + schedstat_add(cfs_rq, exec_clock, delta_exec); + + curr->vruntime += calc_delta_fair(delta_exec, curr); + update_min_vruntime(cfs_rq); + if (entity_is_task(curr)) { struct task_struct *curtask = task_of(curr); @@ -716,7 +727,7 @@ static void update_curr(struct cfs_rq *cfs_rq) static inline void update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se) { - schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock); + schedstat_set(se->statistics.wait_start, rq_clock(rq_of(cfs_rq))); } /* @@ -736,14 +747,14 @@ static void update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se) { schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max, - rq_of(cfs_rq)->clock - se->statistics.wait_start)); + rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start)); schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1); schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum + - rq_of(cfs_rq)->clock - se->statistics.wait_start); + rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start); #ifdef CONFIG_SCHEDSTATS if (entity_is_task(se)) { trace_sched_stat_wait(task_of(se), - rq_of(cfs_rq)->clock - se->statistics.wait_start); + rq_clock(rq_of(cfs_rq)) - se->statistics.wait_start); } #endif schedstat_set(se->statistics.wait_start, 0); @@ -769,119 +780,1292 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) /* * We are starting a new run period: */ - se->exec_start = rq_of(cfs_rq)->clock_task; + se->exec_start = rq_clock_task(rq_of(cfs_rq)); } /************************************************** * Scheduling class queueing methods: */ -#if defined CONFIG_SMP && defined CONFIG_FAIR_GROUP_SCHED -static void -add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight) +#ifdef CONFIG_NUMA_BALANCING +/* + * Approximate time to scan a full NUMA task in ms. The task scan period is + * calculated based on the tasks virtual memory size and + * numa_balancing_scan_size. + */ +unsigned int sysctl_numa_balancing_scan_period_min = 1000; +unsigned int sysctl_numa_balancing_scan_period_max = 60000; + +/* Portion of address space to scan in MB */ +unsigned int sysctl_numa_balancing_scan_size = 256; + +/* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */ +unsigned int sysctl_numa_balancing_scan_delay = 1000; + +static unsigned int task_nr_scan_windows(struct task_struct *p) { - cfs_rq->task_weight += weight; + unsigned long rss = 0; + unsigned long nr_scan_pages; + + /* + * Calculations based on RSS as non-present and empty pages are skipped + * by the PTE scanner and NUMA hinting faults should be trapped based + * on resident pages + */ + nr_scan_pages = sysctl_numa_balancing_scan_size << (20 - PAGE_SHIFT); + rss = get_mm_rss(p->mm); + if (!rss) + rss = nr_scan_pages; + + rss = round_up(rss, nr_scan_pages); + return rss / nr_scan_pages; } -#else -static inline void -add_cfs_task_weight(struct cfs_rq *cfs_rq, unsigned long weight) + +/* For sanitys sake, never scan more PTEs than MAX_SCAN_WINDOW MB/sec. */ +#define MAX_SCAN_WINDOW 2560 + +static unsigned int task_scan_min(struct task_struct *p) { + unsigned int scan, floor; + unsigned int windows = 1; + + if (sysctl_numa_balancing_scan_size < MAX_SCAN_WINDOW) + windows = MAX_SCAN_WINDOW / sysctl_numa_balancing_scan_size; + floor = 1000 / windows; + + scan = sysctl_numa_balancing_scan_period_min / task_nr_scan_windows(p); + return max_t(unsigned int, floor, scan); } -#endif -static void -account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) +static unsigned int task_scan_max(struct task_struct *p) { - update_load_add(&cfs_rq->load, se->load.weight); - if (!parent_entity(se)) - update_load_add(&rq_of(cfs_rq)->load, se->load.weight); - if (entity_is_task(se)) { - add_cfs_task_weight(cfs_rq, se->load.weight); - list_add(&se->group_node, &cfs_rq->tasks); + unsigned int smin = task_scan_min(p); + unsigned int smax; + + /* Watch for min being lower than max due to floor calculations */ + smax = sysctl_numa_balancing_scan_period_max / task_nr_scan_windows(p); + return max(smin, smax); +} + +static void account_numa_enqueue(struct rq *rq, struct task_struct *p) +{ + rq->nr_numa_running += (p->numa_preferred_nid != -1); + rq->nr_preferred_running += (p->numa_preferred_nid == task_node(p)); +} + +static void account_numa_dequeue(struct rq *rq, struct task_struct *p) +{ + rq->nr_numa_running -= (p->numa_preferred_nid != -1); + rq->nr_preferred_running -= (p->numa_preferred_nid == task_node(p)); +} + +struct numa_group { + atomic_t refcount; + + spinlock_t lock; /* nr_tasks, tasks */ + int nr_tasks; + pid_t gid; + struct list_head task_list; + + struct rcu_head rcu; + nodemask_t active_nodes; + unsigned long total_faults; + /* + * Faults_cpu is used to decide whether memory should move + * towards the CPU. As a consequence, these stats are weighted + * more by CPU use than by memory faults. + */ + unsigned long *faults_cpu; + unsigned long faults[0]; +}; + +/* Shared or private faults. */ +#define NR_NUMA_HINT_FAULT_TYPES 2 + +/* Memory and CPU locality */ +#define NR_NUMA_HINT_FAULT_STATS (NR_NUMA_HINT_FAULT_TYPES * 2) + +/* Averaged statistics, and temporary buffers. */ +#define NR_NUMA_HINT_FAULT_BUCKETS (NR_NUMA_HINT_FAULT_STATS * 2) + +pid_t task_numa_group_id(struct task_struct *p) +{ + return p->numa_group ? p->numa_group->gid : 0; +} + +static inline int task_faults_idx(int nid, int priv) +{ + return NR_NUMA_HINT_FAULT_TYPES * nid + priv; +} + +static inline unsigned long task_faults(struct task_struct *p, int nid) +{ + if (!p->numa_faults_memory) + return 0; + + return p->numa_faults_memory[task_faults_idx(nid, 0)] + + p->numa_faults_memory[task_faults_idx(nid, 1)]; +} + +static inline unsigned long group_faults(struct task_struct *p, int nid) +{ + if (!p->numa_group) + return 0; + + return p->numa_group->faults[task_faults_idx(nid, 0)] + + p->numa_group->faults[task_faults_idx(nid, 1)]; +} + +static inline unsigned long group_faults_cpu(struct numa_group *group, int nid) +{ + return group->faults_cpu[task_faults_idx(nid, 0)] + + group->faults_cpu[task_faults_idx(nid, 1)]; +} + +/* + * These return the fraction of accesses done by a particular task, or + * task group, on a particular numa node. The group weight is given a + * larger multiplier, in order to group tasks together that are almost + * evenly spread out between numa nodes. + */ +static inline unsigned long task_weight(struct task_struct *p, int nid) +{ + unsigned long total_faults; + + if (!p->numa_faults_memory) + return 0; + + total_faults = p->total_numa_faults; + + if (!total_faults) + return 0; + + return 1000 * task_faults(p, nid) / total_faults; +} + +static inline unsigned long group_weight(struct task_struct *p, int nid) +{ + if (!p->numa_group || !p->numa_group->total_faults) + return 0; + + return 1000 * group_faults(p, nid) / p->numa_group->total_faults; +} + +bool should_numa_migrate_memory(struct task_struct *p, struct page * page, + int src_nid, int dst_cpu) +{ + struct numa_group *ng = p->numa_group; + int dst_nid = cpu_to_node(dst_cpu); + int last_cpupid, this_cpupid; + + this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid); + + /* + * Multi-stage node selection is used in conjunction with a periodic + * migration fault to build a temporal task<->page relation. By using + * a two-stage filter we remove short/unlikely relations. + * + * Using P(p) ~ n_p / n_t as per frequentist probability, we can equate + * a task's usage of a particular page (n_p) per total usage of this + * page (n_t) (in a given time-span) to a probability. + * + * Our periodic faults will sample this probability and getting the + * same result twice in a row, given these samples are fully + * independent, is then given by P(n)^2, provided our sample period + * is sufficiently short compared to the usage pattern. + * + * This quadric squishes small probabilities, making it less likely we + * act on an unlikely task<->page relation. + */ + last_cpupid = page_cpupid_xchg_last(page, this_cpupid); + if (!cpupid_pid_unset(last_cpupid) && + cpupid_to_nid(last_cpupid) != dst_nid) + return false; + + /* Always allow migrate on private faults */ + if (cpupid_match_pid(p, last_cpupid)) + return true; + + /* A shared fault, but p->numa_group has not been set up yet. */ + if (!ng) + return true; + + /* + * Do not migrate if the destination is not a node that + * is actively used by this numa group. + */ + if (!node_isset(dst_nid, ng->active_nodes)) + return false; + + /* + * Source is a node that is not actively used by this + * numa group, while the destination is. Migrate. + */ + if (!node_isset(src_nid, ng->active_nodes)) + return true; + + /* + * Both source and destination are nodes in active + * use by this numa group. Maximize memory bandwidth + * by migrating from more heavily used groups, to less + * heavily used ones, spreading the load around. + * Use a 1/4 hysteresis to avoid spurious page movement. + */ + return group_faults(p, dst_nid) < (group_faults(p, src_nid) * 3 / 4); +} + +static unsigned long weighted_cpuload(const int cpu); +static unsigned long source_load(int cpu, int type); +static unsigned long target_load(int cpu, int type); +static unsigned long capacity_of(int cpu); +static long effective_load(struct task_group *tg, int cpu, long wl, long wg); + +/* Cached statistics for all CPUs within a node */ +struct numa_stats { + unsigned long nr_running; + unsigned long load; + + /* Total compute capacity of CPUs on a node */ + unsigned long compute_capacity; + + /* Approximate capacity in terms of runnable tasks on a node */ + unsigned long task_capacity; + int has_free_capacity; +}; + +/* + * XXX borrowed from update_sg_lb_stats + */ +static void update_numa_stats(struct numa_stats *ns, int nid) +{ + int cpu, cpus = 0; + + memset(ns, 0, sizeof(*ns)); + for_each_cpu(cpu, cpumask_of_node(nid)) { + struct rq *rq = cpu_rq(cpu); + + ns->nr_running += rq->nr_running; + ns->load += weighted_cpuload(cpu); + ns->compute_capacity += capacity_of(cpu); + + cpus++; } - cfs_rq->nr_running++; + + /* + * If we raced with hotplug and there are no CPUs left in our mask + * the @ns structure is NULL'ed and task_numa_compare() will + * not find this node attractive. + * + * We'll either bail at !has_free_capacity, or we'll detect a huge + * imbalance and bail there. + */ + if (!cpus) + return; + + ns->load = (ns->load * SCHED_CAPACITY_SCALE) / ns->compute_capacity; + ns->task_capacity = + DIV_ROUND_CLOSEST(ns->compute_capacity, SCHED_CAPACITY_SCALE); + ns->has_free_capacity = (ns->nr_running < ns->task_capacity); } -static void -account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) +struct task_numa_env { + struct task_struct *p; + + int src_cpu, src_nid; + int dst_cpu, dst_nid; + + struct numa_stats src_stats, dst_stats; + + int imbalance_pct; + + struct task_struct *best_task; + long best_imp; + int best_cpu; +}; + +static void task_numa_assign(struct task_numa_env *env, + struct task_struct *p, long imp) { - update_load_sub(&cfs_rq->load, se->load.weight); - if (!parent_entity(se)) - update_load_sub(&rq_of(cfs_rq)->load, se->load.weight); - if (entity_is_task(se)) { - add_cfs_task_weight(cfs_rq, -se->load.weight); - list_del_init(&se->group_node); + if (env->best_task) + put_task_struct(env->best_task); + if (p) + get_task_struct(p); + + env->best_task = p; + env->best_imp = imp; + env->best_cpu = env->dst_cpu; +} + +static bool load_too_imbalanced(long orig_src_load, long orig_dst_load, + long src_load, long dst_load, + struct task_numa_env *env) +{ + long imb, old_imb; + + /* We care about the slope of the imbalance, not the direction. */ + if (dst_load < src_load) + swap(dst_load, src_load); + + /* Is the difference below the threshold? */ + imb = dst_load * 100 - src_load * env->imbalance_pct; + if (imb <= 0) + return false; + + /* + * The imbalance is above the allowed threshold. + * Compare it with the old imbalance. + */ + if (orig_dst_load < orig_src_load) + swap(orig_dst_load, orig_src_load); + + old_imb = orig_dst_load * 100 - orig_src_load * env->imbalance_pct; + + /* Would this change make things worse? */ + return (imb > old_imb); +} + +/* + * This checks if the overall compute and NUMA accesses of the system would + * be improved if the source tasks was migrated to the target dst_cpu taking + * into account that it might be best if task running on the dst_cpu should + * be exchanged with the source task + */ +static void task_numa_compare(struct task_numa_env *env, + long taskimp, long groupimp) +{ + struct rq *src_rq = cpu_rq(env->src_cpu); + struct rq *dst_rq = cpu_rq(env->dst_cpu); + struct task_struct *cur; + long orig_src_load, src_load; + long orig_dst_load, dst_load; + long load; + long imp = (groupimp > 0) ? groupimp : taskimp; + + rcu_read_lock(); + cur = ACCESS_ONCE(dst_rq->curr); + if (cur->pid == 0) /* idle */ + cur = NULL; + + /* + * "imp" is the fault differential for the source task between the + * source and destination node. Calculate the total differential for + * the source task and potential destination task. The more negative + * the value is, the more rmeote accesses that would be expected to + * be incurred if the tasks were swapped. + */ + if (cur) { + /* Skip this swap candidate if cannot move to the source cpu */ + if (!cpumask_test_cpu(env->src_cpu, tsk_cpus_allowed(cur))) + goto unlock; + + /* + * If dst and source tasks are in the same NUMA group, or not + * in any group then look only at task weights. + */ + if (cur->numa_group == env->p->numa_group) { + imp = taskimp + task_weight(cur, env->src_nid) - + task_weight(cur, env->dst_nid); + /* + * Add some hysteresis to prevent swapping the + * tasks within a group over tiny differences. + */ + if (cur->numa_group) + imp -= imp/16; + } else { + /* + * Compare the group weights. If a task is all by + * itself (not part of a group), use the task weight + * instead. + */ + if (env->p->numa_group) + imp = groupimp; + else + imp = taskimp; + + if (cur->numa_group) + imp += group_weight(cur, env->src_nid) - + group_weight(cur, env->dst_nid); + else + imp += task_weight(cur, env->src_nid) - + task_weight(cur, env->dst_nid); + } } - cfs_rq->nr_running--; + + if (imp < env->best_imp) + goto unlock; + + if (!cur) { + /* Is there capacity at our destination? */ + if (env->src_stats.has_free_capacity && + !env->dst_stats.has_free_capacity) + goto unlock; + + goto balance; + } + + /* Balance doesn't matter much if we're running a task per cpu */ + if (src_rq->nr_running == 1 && dst_rq->nr_running == 1) + goto assign; + + /* + * In the overloaded case, try and keep the load balanced. + */ +balance: + orig_dst_load = env->dst_stats.load; + orig_src_load = env->src_stats.load; + + /* XXX missing capacity terms */ + load = task_h_load(env->p); + dst_load = orig_dst_load + load; + src_load = orig_src_load - load; + + if (cur) { + load = task_h_load(cur); + dst_load -= load; + src_load += load; + } + + if (load_too_imbalanced(orig_src_load, orig_dst_load, + src_load, dst_load, env)) + goto unlock; + +assign: + task_numa_assign(env, cur, imp); +unlock: + rcu_read_unlock(); } -#ifdef CONFIG_FAIR_GROUP_SCHED -/* we need this in update_cfs_load and load-balance functions below */ -static inline int throttled_hierarchy(struct cfs_rq *cfs_rq); -# ifdef CONFIG_SMP -static void update_cfs_rq_load_contribution(struct cfs_rq *cfs_rq, - int global_update) +static void task_numa_find_cpu(struct task_numa_env *env, + long taskimp, long groupimp) { - struct task_group *tg = cfs_rq->tg; - long load_avg; + int cpu; + + for_each_cpu(cpu, cpumask_of_node(env->dst_nid)) { + /* Skip this CPU if the source task cannot migrate */ + if (!cpumask_test_cpu(cpu, tsk_cpus_allowed(env->p))) + continue; + + env->dst_cpu = cpu; + task_numa_compare(env, taskimp, groupimp); + } +} + +static int task_numa_migrate(struct task_struct *p) +{ + struct task_numa_env env = { + .p = p, + + .src_cpu = task_cpu(p), + .src_nid = task_node(p), + + .imbalance_pct = 112, + + .best_task = NULL, + .best_imp = 0, + .best_cpu = -1 + }; + struct sched_domain *sd; + unsigned long taskweight, groupweight; + int nid, ret; + long taskimp, groupimp; + + /* + * Pick the lowest SD_NUMA domain, as that would have the smallest + * imbalance and would be the first to start moving tasks about. + * + * And we want to avoid any moving of tasks about, as that would create + * random movement of tasks -- counter the numa conditions we're trying + * to satisfy here. + */ + rcu_read_lock(); + sd = rcu_dereference(per_cpu(sd_numa, env.src_cpu)); + if (sd) + env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2; + rcu_read_unlock(); + + /* + * Cpusets can break the scheduler domain tree into smaller + * balance domains, some of which do not cross NUMA boundaries. + * Tasks that are "trapped" in such domains cannot be migrated + * elsewhere, so there is no point in (re)trying. + */ + if (unlikely(!sd)) { + p->numa_preferred_nid = task_node(p); + return -EINVAL; + } + + taskweight = task_weight(p, env.src_nid); + groupweight = group_weight(p, env.src_nid); + update_numa_stats(&env.src_stats, env.src_nid); + env.dst_nid = p->numa_preferred_nid; + taskimp = task_weight(p, env.dst_nid) - taskweight; + groupimp = group_weight(p, env.dst_nid) - groupweight; + update_numa_stats(&env.dst_stats, env.dst_nid); + + /* If the preferred nid has free capacity, try to use it. */ + if (env.dst_stats.has_free_capacity) + task_numa_find_cpu(&env, taskimp, groupimp); + + /* No space available on the preferred nid. Look elsewhere. */ + if (env.best_cpu == -1) { + for_each_online_node(nid) { + if (nid == env.src_nid || nid == p->numa_preferred_nid) + continue; + + /* Only consider nodes where both task and groups benefit */ + taskimp = task_weight(p, nid) - taskweight; + groupimp = group_weight(p, nid) - groupweight; + if (taskimp < 0 && groupimp < 0) + continue; + + env.dst_nid = nid; + update_numa_stats(&env.dst_stats, env.dst_nid); + task_numa_find_cpu(&env, taskimp, groupimp); + } + } + + /* No better CPU than the current one was found. */ + if (env.best_cpu == -1) + return -EAGAIN; + + /* + * If the task is part of a workload that spans multiple NUMA nodes, + * and is migrating into one of the workload's active nodes, remember + * this node as the task's preferred numa node, so the workload can + * settle down. + * A task that migrated to a second choice node will be better off + * trying for a better one later. Do not set the preferred node here. + */ + if (p->numa_group && node_isset(env.dst_nid, p->numa_group->active_nodes)) + sched_setnuma(p, env.dst_nid); + + /* + * Reset the scan period if the task is being rescheduled on an + * alternative node to recheck if the tasks is now properly placed. + */ + p->numa_scan_period = task_scan_min(p); + + if (env.best_task == NULL) { + ret = migrate_task_to(p, env.best_cpu); + if (ret != 0) + trace_sched_stick_numa(p, env.src_cpu, env.best_cpu); + return ret; + } + + ret = migrate_swap(p, env.best_task); + if (ret != 0) + trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task)); + put_task_struct(env.best_task); + return ret; +} + +/* Attempt to migrate a task to a CPU on the preferred node. */ +static void numa_migrate_preferred(struct task_struct *p) +{ + unsigned long interval = HZ; + + /* This task has no NUMA fault statistics yet */ + if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults_memory)) + return; + + /* Periodically retry migrating the task to the preferred node */ + interval = min(interval, msecs_to_jiffies(p->numa_scan_period) / 16); + p->numa_migrate_retry = jiffies + interval; + + /* Success if task is already running on preferred CPU */ + if (task_node(p) == p->numa_preferred_nid) + return; + + /* Otherwise, try migrate to a CPU on the preferred node */ + task_numa_migrate(p); +} + +/* + * Find the nodes on which the workload is actively running. We do this by + * tracking the nodes from which NUMA hinting faults are triggered. This can + * be different from the set of nodes where the workload's memory is currently + * located. + * + * The bitmask is used to make smarter decisions on when to do NUMA page + * migrations, To prevent flip-flopping, and excessive page migrations, nodes + * are added when they cause over 6/16 of the maximum number of faults, but + * only removed when they drop below 3/16. + */ +static void update_numa_active_node_mask(struct numa_group *numa_group) +{ + unsigned long faults, max_faults = 0; + int nid; + + for_each_online_node(nid) { + faults = group_faults_cpu(numa_group, nid); + if (faults > max_faults) + max_faults = faults; + } + + for_each_online_node(nid) { + faults = group_faults_cpu(numa_group, nid); + if (!node_isset(nid, numa_group->active_nodes)) { + if (faults > max_faults * 6 / 16) + node_set(nid, numa_group->active_nodes); + } else if (faults < max_faults * 3 / 16) + node_clear(nid, numa_group->active_nodes); + } +} + +/* + * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS + * increments. The more local the fault statistics are, the higher the scan + * period will be for the next scan window. If local/remote ratio is below + * NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS) the + * scan period will decrease + */ +#define NUMA_PERIOD_SLOTS 10 +#define NUMA_PERIOD_THRESHOLD 3 + +/* + * Increase the scan period (slow down scanning) if the majority of + * our memory is already on our local node, or if the majority of + * the page accesses are shared with other processes. + * Otherwise, decrease the scan period. + */ +static void update_task_scan_period(struct task_struct *p, + unsigned long shared, unsigned long private) +{ + unsigned int period_slot; + int ratio; + int diff; + + unsigned long remote = p->numa_faults_locality[0]; + unsigned long local = p->numa_faults_locality[1]; + + /* + * If there were no record hinting faults then either the task is + * completely idle or all activity is areas that are not of interest + * to automatic numa balancing. Scan slower + */ + if (local + shared == 0) { + p->numa_scan_period = min(p->numa_scan_period_max, + p->numa_scan_period << 1); + + p->mm->numa_next_scan = jiffies + + msecs_to_jiffies(p->numa_scan_period); + + return; + } + + /* + * Prepare to scale scan period relative to the current period. + * == NUMA_PERIOD_THRESHOLD scan period stays the same + * < NUMA_PERIOD_THRESHOLD scan period decreases (scan faster) + * >= NUMA_PERIOD_THRESHOLD scan period increases (scan slower) + */ + period_slot = DIV_ROUND_UP(p->numa_scan_period, NUMA_PERIOD_SLOTS); + ratio = (local * NUMA_PERIOD_SLOTS) / (local + remote); + if (ratio >= NUMA_PERIOD_THRESHOLD) { + int slot = ratio - NUMA_PERIOD_THRESHOLD; + if (!slot) + slot = 1; + diff = slot * period_slot; + } else { + diff = -(NUMA_PERIOD_THRESHOLD - ratio) * period_slot; + + /* + * Scale scan rate increases based on sharing. There is an + * inverse relationship between the degree of sharing and + * the adjustment made to the scanning period. Broadly + * speaking the intent is that there is little point + * scanning faster if shared accesses dominate as it may + * simply bounce migrations uselessly + */ + ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared)); + diff = (diff * ratio) / NUMA_PERIOD_SLOTS; + } + + p->numa_scan_period = clamp(p->numa_scan_period + diff, + task_scan_min(p), task_scan_max(p)); + memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); +} + +/* + * Get the fraction of time the task has been running since the last + * NUMA placement cycle. The scheduler keeps similar statistics, but + * decays those on a 32ms period, which is orders of magnitude off + * from the dozens-of-seconds NUMA balancing period. Use the scheduler + * stats only if the task is so new there are no NUMA statistics yet. + */ +static u64 numa_get_avg_runtime(struct task_struct *p, u64 *period) +{ + u64 runtime, delta, now; + /* Use the start of this time slice to avoid calculations. */ + now = p->se.exec_start; + runtime = p->se.sum_exec_runtime; + + if (p->last_task_numa_placement) { + delta = runtime - p->last_sum_exec_runtime; + *period = now - p->last_task_numa_placement; + } else { + delta = p->se.avg.runnable_avg_sum; + *period = p->se.avg.runnable_avg_period; + } + + p->last_sum_exec_runtime = runtime; + p->last_task_numa_placement = now; + + return delta; +} + +static void task_numa_placement(struct task_struct *p) +{ + int seq, nid, max_nid = -1, max_group_nid = -1; + unsigned long max_faults = 0, max_group_faults = 0; + unsigned long fault_types[2] = { 0, 0 }; + unsigned long total_faults; + u64 runtime, period; + spinlock_t *group_lock = NULL; + + seq = ACCESS_ONCE(p->mm->numa_scan_seq); + if (p->numa_scan_seq == seq) + return; + p->numa_scan_seq = seq; + p->numa_scan_period_max = task_scan_max(p); + + total_faults = p->numa_faults_locality[0] + + p->numa_faults_locality[1]; + runtime = numa_get_avg_runtime(p, &period); + + /* If the task is part of a group prevent parallel updates to group stats */ + if (p->numa_group) { + group_lock = &p->numa_group->lock; + spin_lock_irq(group_lock); + } + + /* Find the node with the highest number of faults */ + for_each_online_node(nid) { + unsigned long faults = 0, group_faults = 0; + int priv, i; + + for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) { + long diff, f_diff, f_weight; + + i = task_faults_idx(nid, priv); + + /* Decay existing window, copy faults since last scan */ + diff = p->numa_faults_buffer_memory[i] - p->numa_faults_memory[i] / 2; + fault_types[priv] += p->numa_faults_buffer_memory[i]; + p->numa_faults_buffer_memory[i] = 0; + + /* + * Normalize the faults_from, so all tasks in a group + * count according to CPU use, instead of by the raw + * number of faults. Tasks with little runtime have + * little over-all impact on throughput, and thus their + * faults are less important. + */ + f_weight = div64_u64(runtime << 16, period + 1); + f_weight = (f_weight * p->numa_faults_buffer_cpu[i]) / + (total_faults + 1); + f_diff = f_weight - p->numa_faults_cpu[i] / 2; + p->numa_faults_buffer_cpu[i] = 0; + + p->numa_faults_memory[i] += diff; + p->numa_faults_cpu[i] += f_diff; + faults += p->numa_faults_memory[i]; + p->total_numa_faults += diff; + if (p->numa_group) { + /* safe because we can only change our own group */ + p->numa_group->faults[i] += diff; + p->numa_group->faults_cpu[i] += f_diff; + p->numa_group->total_faults += diff; + group_faults += p->numa_group->faults[i]; + } + } + + if (faults > max_faults) { + max_faults = faults; + max_nid = nid; + } + + if (group_faults > max_group_faults) { + max_group_faults = group_faults; + max_group_nid = nid; + } + } + + update_task_scan_period(p, fault_types[0], fault_types[1]); + + if (p->numa_group) { + update_numa_active_node_mask(p->numa_group); + /* + * If the preferred task and group nids are different, + * iterate over the nodes again to find the best place. + */ + if (max_nid != max_group_nid) { + unsigned long weight, max_weight = 0; + + for_each_online_node(nid) { + weight = task_weight(p, nid) + group_weight(p, nid); + if (weight > max_weight) { + max_weight = weight; + max_nid = nid; + } + } + } + + spin_unlock_irq(group_lock); + } + + /* Preferred node as the node with the most faults */ + if (max_faults && max_nid != p->numa_preferred_nid) { + /* Update the preferred nid and migrate task if possible */ + sched_setnuma(p, max_nid); + numa_migrate_preferred(p); + } +} + +static inline int get_numa_group(struct numa_group *grp) +{ + return atomic_inc_not_zero(&grp->refcount); +} + +static inline void put_numa_group(struct numa_group *grp) +{ + if (atomic_dec_and_test(&grp->refcount)) + kfree_rcu(grp, rcu); +} + +static void task_numa_group(struct task_struct *p, int cpupid, int flags, + int *priv) +{ + struct numa_group *grp, *my_grp; + struct task_struct *tsk; + bool join = false; + int cpu = cpupid_to_cpu(cpupid); + int i; + + if (unlikely(!p->numa_group)) { + unsigned int size = sizeof(struct numa_group) + + 4*nr_node_ids*sizeof(unsigned long); + + grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); + if (!grp) + return; + + atomic_set(&grp->refcount, 1); + spin_lock_init(&grp->lock); + INIT_LIST_HEAD(&grp->task_list); + grp->gid = p->pid; + /* Second half of the array tracks nids where faults happen */ + grp->faults_cpu = grp->faults + NR_NUMA_HINT_FAULT_TYPES * + nr_node_ids; + + node_set(task_node(current), grp->active_nodes); + + for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) + grp->faults[i] = p->numa_faults_memory[i]; + + grp->total_faults = p->total_numa_faults; + + list_add(&p->numa_entry, &grp->task_list); + grp->nr_tasks++; + rcu_assign_pointer(p->numa_group, grp); + } - load_avg = div64_u64(cfs_rq->load_avg, cfs_rq->load_period+1); - load_avg -= cfs_rq->load_contribution; + rcu_read_lock(); + tsk = ACCESS_ONCE(cpu_rq(cpu)->curr); + + if (!cpupid_match_pid(tsk, cpupid)) + goto no_join; + + grp = rcu_dereference(tsk->numa_group); + if (!grp) + goto no_join; + + my_grp = p->numa_group; + if (grp == my_grp) + goto no_join; + + /* + * Only join the other group if its bigger; if we're the bigger group, + * the other task will join us. + */ + if (my_grp->nr_tasks > grp->nr_tasks) + goto no_join; + + /* + * Tie-break on the grp address. + */ + if (my_grp->nr_tasks == grp->nr_tasks && my_grp > grp) + goto no_join; + + /* Always join threads in the same process. */ + if (tsk->mm == current->mm) + join = true; + + /* Simple filter to avoid false positives due to PID collisions */ + if (flags & TNF_SHARED) + join = true; + + /* Update priv based on whether false sharing was detected */ + *priv = !join; + + if (join && !get_numa_group(grp)) + goto no_join; - if (global_update || abs(load_avg) > cfs_rq->load_contribution / 8) { - atomic_add(load_avg, &tg->load_weight); - cfs_rq->load_contribution += load_avg; + rcu_read_unlock(); + + if (!join) + return; + + BUG_ON(irqs_disabled()); + double_lock_irq(&my_grp->lock, &grp->lock); + + for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) { + my_grp->faults[i] -= p->numa_faults_memory[i]; + grp->faults[i] += p->numa_faults_memory[i]; } + my_grp->total_faults -= p->total_numa_faults; + grp->total_faults += p->total_numa_faults; + + list_move(&p->numa_entry, &grp->task_list); + my_grp->nr_tasks--; + grp->nr_tasks++; + + spin_unlock(&my_grp->lock); + spin_unlock_irq(&grp->lock); + + rcu_assign_pointer(p->numa_group, grp); + + put_numa_group(my_grp); + return; + +no_join: + rcu_read_unlock(); + return; } -static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update) +void task_numa_free(struct task_struct *p) { - u64 period = sysctl_sched_shares_window; - u64 now, delta; - unsigned long load = cfs_rq->load.weight; + struct numa_group *grp = p->numa_group; + void *numa_faults = p->numa_faults_memory; + unsigned long flags; + int i; + + if (grp) { + spin_lock_irqsave(&grp->lock, flags); + for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) + grp->faults[i] -= p->numa_faults_memory[i]; + grp->total_faults -= p->total_numa_faults; + + list_del(&p->numa_entry); + grp->nr_tasks--; + spin_unlock_irqrestore(&grp->lock, flags); + rcu_assign_pointer(p->numa_group, NULL); + put_numa_group(grp); + } + + p->numa_faults_memory = NULL; + p->numa_faults_buffer_memory = NULL; + p->numa_faults_cpu= NULL; + p->numa_faults_buffer_cpu = NULL; + kfree(numa_faults); +} + +/* + * Got a PROT_NONE fault for a page on @node. + */ +void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) +{ + struct task_struct *p = current; + bool migrated = flags & TNF_MIGRATED; + int cpu_node = task_node(current); + int local = !!(flags & TNF_FAULT_LOCAL); + int priv; + + if (!numabalancing_enabled) + return; + + /* for example, ksmd faulting in a user's mm */ + if (!p->mm) + return; - if (cfs_rq->tg == &root_task_group || throttled_hierarchy(cfs_rq)) + /* Do not worry about placement if exiting */ + if (p->state == TASK_DEAD) return; - now = rq_of(cfs_rq)->clock_task; - delta = now - cfs_rq->load_stamp; + /* Allocate buffer to track faults on a per-node basis */ + if (unlikely(!p->numa_faults_memory)) { + int size = sizeof(*p->numa_faults_memory) * + NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids; + + p->numa_faults_memory = kzalloc(size, GFP_KERNEL|__GFP_NOWARN); + if (!p->numa_faults_memory) + return; - /* truncate load history at 4 idle periods */ - if (cfs_rq->load_stamp > cfs_rq->load_last && - now - cfs_rq->load_last > 4 * period) { - cfs_rq->load_period = 0; - cfs_rq->load_avg = 0; - delta = period - 1; + BUG_ON(p->numa_faults_buffer_memory); + /* + * The averaged statistics, shared & private, memory & cpu, + * occupy the first half of the array. The second half of the + * array is for current counters, which are averaged into the + * first set by task_numa_placement. + */ + p->numa_faults_cpu = p->numa_faults_memory + (2 * nr_node_ids); + p->numa_faults_buffer_memory = p->numa_faults_memory + (4 * nr_node_ids); + p->numa_faults_buffer_cpu = p->numa_faults_memory + (6 * nr_node_ids); + p->total_numa_faults = 0; + memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); } - cfs_rq->load_stamp = now; - cfs_rq->load_unacc_exec_time = 0; - cfs_rq->load_period += delta; - if (load) { - cfs_rq->load_last = now; - cfs_rq->load_avg += delta * load; + /* + * First accesses are treated as private, otherwise consider accesses + * to be private if the accessing pid has not changed + */ + if (unlikely(last_cpupid == (-1 & LAST_CPUPID_MASK))) { + priv = 1; + } else { + priv = cpupid_match_pid(p, last_cpupid); + if (!priv && !(flags & TNF_NO_GROUP)) + task_numa_group(p, last_cpupid, flags, &priv); } - /* consider updating load contribution on each fold or truncate */ - if (global_update || cfs_rq->load_period > period - || !cfs_rq->load_period) - update_cfs_rq_load_contribution(cfs_rq, global_update); + /* + * If a workload spans multiple NUMA nodes, a shared fault that + * occurs wholly within the set of nodes that the workload is + * actively using should be counted as local. This allows the + * scan rate to slow down when a workload has settled down. + */ + if (!priv && !local && p->numa_group && + node_isset(cpu_node, p->numa_group->active_nodes) && + node_isset(mem_node, p->numa_group->active_nodes)) + local = 1; + + task_numa_placement(p); + + /* + * Retry task to preferred node migration periodically, in case it + * case it previously failed, or the scheduler moved us. + */ + if (time_after(jiffies, p->numa_migrate_retry)) + numa_migrate_preferred(p); + + if (migrated) + p->numa_pages_migrated += pages; + + p->numa_faults_buffer_memory[task_faults_idx(mem_node, priv)] += pages; + p->numa_faults_buffer_cpu[task_faults_idx(cpu_node, priv)] += pages; + p->numa_faults_locality[local] += pages; +} + +static void reset_ptenuma_scan(struct task_struct *p) +{ + ACCESS_ONCE(p->mm->numa_scan_seq)++; + p->mm->numa_scan_offset = 0; +} + +/* + * The expensive part of numa migration is done from task_work context. + * Triggered from task_tick_numa(). + */ +void task_numa_work(struct callback_head *work) +{ + unsigned long migrate, next_scan, now = jiffies; + struct task_struct *p = current; + struct mm_struct *mm = p->mm; + struct vm_area_struct *vma; + unsigned long start, end; + unsigned long nr_pte_updates = 0; + long pages; + + WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work)); + + work->next = work; /* protect against double add */ + /* + * Who cares about NUMA placement when they're dying. + * + * NOTE: make sure not to dereference p->mm before this check, + * exit_task_work() happens _after_ exit_mm() so we could be called + * without p->mm even though we still had it when we enqueued this + * work. + */ + if (p->flags & PF_EXITING) + return; + + if (!mm->numa_next_scan) { + mm->numa_next_scan = now + + msecs_to_jiffies(sysctl_numa_balancing_scan_delay); + } + + /* + * Enforce maximal scan/migration frequency.. + */ + migrate = mm->numa_next_scan; + if (time_before(now, migrate)) + return; + + if (p->numa_scan_period == 0) { + p->numa_scan_period_max = task_scan_max(p); + p->numa_scan_period = task_scan_min(p); + } + + next_scan = now + msecs_to_jiffies(p->numa_scan_period); + if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate) + return; + + /* + * Delay this task enough that another task of this mm will likely win + * the next time around. + */ + p->node_stamp += 2 * TICK_NSEC; + + start = mm->numa_scan_offset; + pages = sysctl_numa_balancing_scan_size; + pages <<= 20 - PAGE_SHIFT; /* MB in pages */ + if (!pages) + return; + + down_read(&mm->mmap_sem); + vma = find_vma(mm, start); + if (!vma) { + reset_ptenuma_scan(p); + start = 0; + vma = mm->mmap; + } + for (; vma; vma = vma->vm_next) { + if (!vma_migratable(vma) || !vma_policy_mof(p, vma)) + continue; + + /* + * Shared library pages mapped by multiple processes are not + * migrated as it is expected they are cache replicated. Avoid + * hinting faults in read-only file-backed mappings or the vdso + * as migrating the pages will be of marginal benefit. + */ + if (!vma->vm_mm || + (vma->vm_file && (vma->vm_flags & (VM_READ|VM_WRITE)) == (VM_READ))) + continue; - while (cfs_rq->load_period > period) { /* - * Inline assembly required to prevent the compiler - * optimising this loop into a divmod call. - * See __iter_div_u64_rem() for another example of this. + * Skip inaccessible VMAs to avoid any confusion between + * PROT_NONE and NUMA hinting ptes */ - asm("" : "+rm" (cfs_rq->load_period)); - cfs_rq->load_period /= 2; - cfs_rq->load_avg /= 2; + if (!(vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE))) + continue; + + do { + start = max(start, vma->vm_start); + end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE); + end = min(end, vma->vm_end); + nr_pte_updates += change_prot_numa(vma, start, end); + + /* + * Scan sysctl_numa_balancing_scan_size but ensure that + * at least one PTE is updated so that unused virtual + * address space is quickly skipped. + */ + if (nr_pte_updates) + pages -= (end - start) >> PAGE_SHIFT; + + start = end; + if (pages <= 0) + goto out; + + cond_resched(); + } while (end != vma->vm_end); + } + +out: + /* + * It is possible to reach the end of the VMA list but the last few + * VMAs are not guaranteed to the vma_migratable. If they are not, we + * would find the !migratable VMA on the next scan but not reset the + * scanner to the start so check it now. + */ + if (vma) + mm->numa_scan_offset = start; + else + reset_ptenuma_scan(p); + up_read(&mm->mmap_sem); +} + +/* + * Drive the periodic memory faults.. + */ +void task_tick_numa(struct rq *rq, struct task_struct *curr) +{ + struct callback_head *work = &curr->numa_work; + u64 period, now; + + /* + * We don't care about NUMA placement if we don't have memory. + */ + if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work) + return; + + /* + * Using runtime rather than walltime has the dual advantage that + * we (mostly) drive the selection from busy threads and that the + * task needs to have done some actual work before we bother with + * NUMA placement. + */ + now = curr->se.sum_exec_runtime; + period = (u64)curr->numa_scan_period * NSEC_PER_MSEC; + + if (now - curr->node_stamp > period) { + if (!curr->node_stamp) + curr->numa_scan_period = task_scan_min(curr); + curr->node_stamp += period; + + if (!time_before(jiffies, curr->mm->numa_next_scan)) { + init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */ + task_work_add(curr, work, true); + } } +} +#else +static void task_tick_numa(struct rq *rq, struct task_struct *curr) +{ +} - if (!cfs_rq->curr && !cfs_rq->nr_running && !cfs_rq->load_avg) - list_del_leaf_cfs_rq(cfs_rq); +static inline void account_numa_enqueue(struct rq *rq, struct task_struct *p) +{ +} + +static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p) +{ } +#endif /* CONFIG_NUMA_BALANCING */ +static void +account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) +{ + update_load_add(&cfs_rq->load, se->load.weight); + if (!parent_entity(se)) + update_load_add(&rq_of(cfs_rq)->load, se->load.weight); +#ifdef CONFIG_SMP + if (entity_is_task(se)) { + struct rq *rq = rq_of(cfs_rq); + + account_numa_enqueue(rq, task_of(se)); + list_add(&se->group_node, &rq->cfs_tasks); + } +#endif + cfs_rq->nr_running++; +} + +static void +account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se) +{ + update_load_sub(&cfs_rq->load, se->load.weight); + if (!parent_entity(se)) + update_load_sub(&rq_of(cfs_rq)->load, se->load.weight); + if (entity_is_task(se)) { + account_numa_dequeue(rq_of(cfs_rq), task_of(se)); + list_del_init(&se->group_node); + } + cfs_rq->nr_running--; +} + +#ifdef CONFIG_FAIR_GROUP_SCHED +# ifdef CONFIG_SMP static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq) { long tg_weight; @@ -891,8 +2075,8 @@ static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq) * to gain a more accurate current total weight. See * update_cfs_rq_load_contribution(). */ - tg_weight = atomic_read(&tg->load_weight); - tg_weight -= cfs_rq->load_contribution; + tg_weight = atomic_long_read(&tg->load_avg); + tg_weight -= cfs_rq->tg_load_contrib; tg_weight += cfs_rq->load.weight; return tg_weight; @@ -916,27 +2100,11 @@ static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) return shares; } - -static void update_entity_shares_tick(struct cfs_rq *cfs_rq) -{ - if (cfs_rq->load_unacc_exec_time > sysctl_sched_shares_window) { - update_cfs_load(cfs_rq, 0); - update_cfs_shares(cfs_rq); - } -} # else /* CONFIG_SMP */ -static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update) -{ -} - static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg) { return tg->shares; } - -static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq) -{ -} # endif /* CONFIG_SMP */ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, unsigned long weight) @@ -954,6 +2122,8 @@ static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, account_entity_enqueue(cfs_rq, se); } +static inline int throttled_hierarchy(struct cfs_rq *cfs_rq); + static void update_cfs_shares(struct cfs_rq *cfs_rq) { struct task_group *tg; @@ -973,19 +2143,513 @@ static void update_cfs_shares(struct cfs_rq *cfs_rq) reweight_entity(cfs_rq_of(se), se, shares); } #else /* CONFIG_FAIR_GROUP_SCHED */ -static void update_cfs_load(struct cfs_rq *cfs_rq, int global_update) +static inline void update_cfs_shares(struct cfs_rq *cfs_rq) { } +#endif /* CONFIG_FAIR_GROUP_SCHED */ -static inline void update_cfs_shares(struct cfs_rq *cfs_rq) +#ifdef CONFIG_SMP +/* + * We choose a half-life close to 1 scheduling period. + * Note: The tables below are dependent on this value. + */ +#define LOAD_AVG_PERIOD 32 +#define LOAD_AVG_MAX 47742 /* maximum possible load avg */ +#define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */ + +/* Precomputed fixed inverse multiplies for multiplication by y^n */ +static const u32 runnable_avg_yN_inv[] = { + 0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6, + 0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85, + 0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581, + 0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9, + 0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80, + 0x85aac367, 0x82cd8698, +}; + +/* + * Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent + * over-estimates when re-combining. + */ +static const u32 runnable_avg_yN_sum[] = { + 0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103, + 9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082, + 17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371, +}; + +/* + * Approximate: + * val * y^n, where y^32 ~= 0.5 (~1 scheduling period) + */ +static __always_inline u64 decay_load(u64 val, u64 n) +{ + unsigned int local_n; + + if (!n) + return val; + else if (unlikely(n > LOAD_AVG_PERIOD * 63)) + return 0; + + /* after bounds checking we can collapse to 32-bit */ + local_n = n; + + /* + * As y^PERIOD = 1/2, we can combine + * y^n = 1/2^(n/PERIOD) * k^(n%PERIOD) + * With a look-up table which covers k^n (n<PERIOD) + * + * To achieve constant time decay_load. + */ + if (unlikely(local_n >= LOAD_AVG_PERIOD)) { + val >>= local_n / LOAD_AVG_PERIOD; + local_n %= LOAD_AVG_PERIOD; + } + + val *= runnable_avg_yN_inv[local_n]; + /* We don't use SRR here since we always want to round down. */ + return val >> 32; +} + +/* + * For updates fully spanning n periods, the contribution to runnable + * average will be: \Sum 1024*y^n + * + * We can compute this reasonably efficiently by combining: + * y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD} + */ +static u32 __compute_runnable_contrib(u64 n) +{ + u32 contrib = 0; + + if (likely(n <= LOAD_AVG_PERIOD)) + return runnable_avg_yN_sum[n]; + else if (unlikely(n >= LOAD_AVG_MAX_N)) + return LOAD_AVG_MAX; + + /* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */ + do { + contrib /= 2; /* y^LOAD_AVG_PERIOD = 1/2 */ + contrib += runnable_avg_yN_sum[LOAD_AVG_PERIOD]; + + n -= LOAD_AVG_PERIOD; + } while (n > LOAD_AVG_PERIOD); + + contrib = decay_load(contrib, n); + return contrib + runnable_avg_yN_sum[n]; +} + +/* + * We can represent the historical contribution to runnable average as the + * coefficients of a geometric series. To do this we sub-divide our runnable + * history into segments of approximately 1ms (1024us); label the segment that + * occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g. + * + * [<- 1024us ->|<- 1024us ->|<- 1024us ->| ... + * p0 p1 p2 + * (now) (~1ms ago) (~2ms ago) + * + * Let u_i denote the fraction of p_i that the entity was runnable. + * + * We then designate the fractions u_i as our co-efficients, yielding the + * following representation of historical load: + * u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ... + * + * We choose y based on the with of a reasonably scheduling period, fixing: + * y^32 = 0.5 + * + * This means that the contribution to load ~32ms ago (u_32) will be weighted + * approximately half as much as the contribution to load within the last ms + * (u_0). + * + * When a period "rolls over" and we have new u_0`, multiplying the previous + * sum again by y is sufficient to update: + * load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... ) + * = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}] + */ +static __always_inline int __update_entity_runnable_avg(u64 now, + struct sched_avg *sa, + int runnable) { + u64 delta, periods; + u32 runnable_contrib; + int delta_w, decayed = 0; + + delta = now - sa->last_runnable_update; + /* + * This should only happen when time goes backwards, which it + * unfortunately does during sched clock init when we swap over to TSC. + */ + if ((s64)delta < 0) { + sa->last_runnable_update = now; + return 0; + } + + /* + * Use 1024ns as the unit of measurement since it's a reasonable + * approximation of 1us and fast to compute. + */ + delta >>= 10; + if (!delta) + return 0; + sa->last_runnable_update = now; + + /* delta_w is the amount already accumulated against our next period */ + delta_w = sa->runnable_avg_period % 1024; + if (delta + delta_w >= 1024) { + /* period roll-over */ + decayed = 1; + + /* + * Now that we know we're crossing a period boundary, figure + * out how much from delta we need to complete the current + * period and accrue it. + */ + delta_w = 1024 - delta_w; + if (runnable) + sa->runnable_avg_sum += delta_w; + sa->runnable_avg_period += delta_w; + + delta -= delta_w; + + /* Figure out how many additional periods this update spans */ + periods = delta / 1024; + delta %= 1024; + + sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum, + periods + 1); + sa->runnable_avg_period = decay_load(sa->runnable_avg_period, + periods + 1); + + /* Efficiently calculate \sum (1..n_period) 1024*y^i */ + runnable_contrib = __compute_runnable_contrib(periods); + if (runnable) + sa->runnable_avg_sum += runnable_contrib; + sa->runnable_avg_period += runnable_contrib; + } + + /* Remainder of delta accrued against u_0` */ + if (runnable) + sa->runnable_avg_sum += delta; + sa->runnable_avg_period += delta; + + return decayed; } -static inline void update_entity_shares_tick(struct cfs_rq *cfs_rq) +/* Synchronize an entity's decay with its parenting cfs_rq.*/ +static inline u64 __synchronize_entity_decay(struct sched_entity *se) { + struct cfs_rq *cfs_rq = cfs_rq_of(se); + u64 decays = atomic64_read(&cfs_rq->decay_counter); + + decays -= se->avg.decay_count; + if (!decays) + return 0; + + se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays); + se->avg.decay_count = 0; + + return decays; +} + +#ifdef CONFIG_FAIR_GROUP_SCHED +static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq, + int force_update) +{ + struct task_group *tg = cfs_rq->tg; + long tg_contrib; + + tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg; + tg_contrib -= cfs_rq->tg_load_contrib; + + if (force_update || abs(tg_contrib) > cfs_rq->tg_load_contrib / 8) { + atomic_long_add(tg_contrib, &tg->load_avg); + cfs_rq->tg_load_contrib += tg_contrib; + } +} + +/* + * Aggregate cfs_rq runnable averages into an equivalent task_group + * representation for computing load contributions. + */ +static inline void __update_tg_runnable_avg(struct sched_avg *sa, + struct cfs_rq *cfs_rq) +{ + struct task_group *tg = cfs_rq->tg; + long contrib; + + /* The fraction of a cpu used by this cfs_rq */ + contrib = div_u64((u64)sa->runnable_avg_sum << NICE_0_SHIFT, + sa->runnable_avg_period + 1); + contrib -= cfs_rq->tg_runnable_contrib; + + if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) { + atomic_add(contrib, &tg->runnable_avg); + cfs_rq->tg_runnable_contrib += contrib; + } } + +static inline void __update_group_entity_contrib(struct sched_entity *se) +{ + struct cfs_rq *cfs_rq = group_cfs_rq(se); + struct task_group *tg = cfs_rq->tg; + int runnable_avg; + + u64 contrib; + + contrib = cfs_rq->tg_load_contrib * tg->shares; + se->avg.load_avg_contrib = div_u64(contrib, + atomic_long_read(&tg->load_avg) + 1); + + /* + * For group entities we need to compute a correction term in the case + * that they are consuming <1 cpu so that we would contribute the same + * load as a task of equal weight. + * + * Explicitly co-ordinating this measurement would be expensive, but + * fortunately the sum of each cpus contribution forms a usable + * lower-bound on the true value. + * + * Consider the aggregate of 2 contributions. Either they are disjoint + * (and the sum represents true value) or they are disjoint and we are + * understating by the aggregate of their overlap. + * + * Extending this to N cpus, for a given overlap, the maximum amount we + * understand is then n_i(n_i+1)/2 * w_i where n_i is the number of + * cpus that overlap for this interval and w_i is the interval width. + * + * On a small machine; the first term is well-bounded which bounds the + * total error since w_i is a subset of the period. Whereas on a + * larger machine, while this first term can be larger, if w_i is the + * of consequential size guaranteed to see n_i*w_i quickly converge to + * our upper bound of 1-cpu. + */ + runnable_avg = atomic_read(&tg->runnable_avg); + if (runnable_avg < NICE_0_LOAD) { + se->avg.load_avg_contrib *= runnable_avg; + se->avg.load_avg_contrib >>= NICE_0_SHIFT; + } +} + +static inline void update_rq_runnable_avg(struct rq *rq, int runnable) +{ + __update_entity_runnable_avg(rq_clock_task(rq), &rq->avg, runnable); + __update_tg_runnable_avg(&rq->avg, &rq->cfs); +} +#else /* CONFIG_FAIR_GROUP_SCHED */ +static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq, + int force_update) {} +static inline void __update_tg_runnable_avg(struct sched_avg *sa, + struct cfs_rq *cfs_rq) {} +static inline void __update_group_entity_contrib(struct sched_entity *se) {} +static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {} #endif /* CONFIG_FAIR_GROUP_SCHED */ +static inline void __update_task_entity_contrib(struct sched_entity *se) +{ + u32 contrib; + + /* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */ + contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight); + contrib /= (se->avg.runnable_avg_period + 1); + se->avg.load_avg_contrib = scale_load(contrib); +} + +/* Compute the current contribution to load_avg by se, return any delta */ +static long __update_entity_load_avg_contrib(struct sched_entity *se) +{ + long old_contrib = se->avg.load_avg_contrib; + + if (entity_is_task(se)) { + __update_task_entity_contrib(se); + } else { + __update_tg_runnable_avg(&se->avg, group_cfs_rq(se)); + __update_group_entity_contrib(se); + } + + return se->avg.load_avg_contrib - old_contrib; +} + +static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq, + long load_contrib) +{ + if (likely(load_contrib < cfs_rq->blocked_load_avg)) + cfs_rq->blocked_load_avg -= load_contrib; + else + cfs_rq->blocked_load_avg = 0; +} + +static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq); + +/* Update a sched_entity's runnable average */ +static inline void update_entity_load_avg(struct sched_entity *se, + int update_cfs_rq) +{ + struct cfs_rq *cfs_rq = cfs_rq_of(se); + long contrib_delta; + u64 now; + + /* + * For a group entity we need to use their owned cfs_rq_clock_task() in + * case they are the parent of a throttled hierarchy. + */ + if (entity_is_task(se)) + now = cfs_rq_clock_task(cfs_rq); + else + now = cfs_rq_clock_task(group_cfs_rq(se)); + + if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq)) + return; + + contrib_delta = __update_entity_load_avg_contrib(se); + + if (!update_cfs_rq) + return; + + if (se->on_rq) + cfs_rq->runnable_load_avg += contrib_delta; + else + subtract_blocked_load_contrib(cfs_rq, -contrib_delta); +} + +/* + * Decay the load contributed by all blocked children and account this so that + * their contribution may appropriately discounted when they wake up. + */ +static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update) +{ + u64 now = cfs_rq_clock_task(cfs_rq) >> 20; + u64 decays; + + decays = now - cfs_rq->last_decay; + if (!decays && !force_update) + return; + + if (atomic_long_read(&cfs_rq->removed_load)) { + unsigned long removed_load; + removed_load = atomic_long_xchg(&cfs_rq->removed_load, 0); + subtract_blocked_load_contrib(cfs_rq, removed_load); + } + + if (decays) { + cfs_rq->blocked_load_avg = decay_load(cfs_rq->blocked_load_avg, + decays); + atomic64_add(decays, &cfs_rq->decay_counter); + cfs_rq->last_decay = now; + } + + __update_cfs_rq_tg_load_contrib(cfs_rq, force_update); +} + +/* Add the load generated by se into cfs_rq's child load-average */ +static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, + struct sched_entity *se, + int wakeup) +{ + /* + * We track migrations using entity decay_count <= 0, on a wake-up + * migration we use a negative decay count to track the remote decays + * accumulated while sleeping. + * + * Newly forked tasks are enqueued with se->avg.decay_count == 0, they + * are seen by enqueue_entity_load_avg() as a migration with an already + * constructed load_avg_contrib. + */ + if (unlikely(se->avg.decay_count <= 0)) { + se->avg.last_runnable_update = rq_clock_task(rq_of(cfs_rq)); + if (se->avg.decay_count) { + /* + * In a wake-up migration we have to approximate the + * time sleeping. This is because we can't synchronize + * clock_task between the two cpus, and it is not + * guaranteed to be read-safe. Instead, we can + * approximate this using our carried decays, which are + * explicitly atomically readable. + */ + se->avg.last_runnable_update -= (-se->avg.decay_count) + << 20; + update_entity_load_avg(se, 0); + /* Indicate that we're now synchronized and on-rq */ + se->avg.decay_count = 0; + } + wakeup = 0; + } else { + __synchronize_entity_decay(se); + } + + /* migrated tasks did not contribute to our blocked load */ + if (wakeup) { + subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib); + update_entity_load_avg(se, 0); + } + + cfs_rq->runnable_load_avg += se->avg.load_avg_contrib; + /* we force update consideration on load-balancer moves */ + update_cfs_rq_blocked_load(cfs_rq, !wakeup); +} + +/* + * Remove se's load from this cfs_rq child load-average, if the entity is + * transitioning to a blocked state we track its projected decay using + * blocked_load_avg. + */ +static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, + struct sched_entity *se, + int sleep) +{ + update_entity_load_avg(se, 1); + /* we force update consideration on load-balancer moves */ + update_cfs_rq_blocked_load(cfs_rq, !sleep); + + cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib; + if (sleep) { + cfs_rq->blocked_load_avg += se->avg.load_avg_contrib; + se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter); + } /* migrations, e.g. sleep=0 leave decay_count == 0 */ +} + +/* + * Update the rq's load with the elapsed running time before entering + * idle. if the last scheduled task is not a CFS task, idle_enter will + * be the only way to update the runnable statistic. + */ +void idle_enter_fair(struct rq *this_rq) +{ + update_rq_runnable_avg(this_rq, 1); +} + +/* + * Update the rq's load with the elapsed idle time before a task is + * scheduled. if the newly scheduled task is not a CFS task, idle_exit will + * be the only way to update the runnable statistic. + */ +void idle_exit_fair(struct rq *this_rq) +{ + update_rq_runnable_avg(this_rq, 0); +} + +static int idle_balance(struct rq *this_rq); + +#else /* CONFIG_SMP */ + +static inline void update_entity_load_avg(struct sched_entity *se, + int update_cfs_rq) {} +static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {} +static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, + struct sched_entity *se, + int wakeup) {} +static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, + struct sched_entity *se, + int sleep) {} +static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, + int force_update) {} + +static inline int idle_balance(struct rq *rq) +{ + return 0; +} + +#endif /* CONFIG_SMP */ + static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) { #ifdef CONFIG_SCHEDSTATS @@ -995,7 +2659,7 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) tsk = task_of(se); if (se->statistics.sleep_start) { - u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start; + u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.sleep_start; if ((s64)delta < 0) delta = 0; @@ -1003,6 +2667,7 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) if (unlikely(delta > se->statistics.sleep_max)) se->statistics.sleep_max = delta; + se->statistics.sleep_start = 0; se->statistics.sum_sleep_runtime += delta; if (tsk) { @@ -1011,7 +2676,7 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) } } if (se->statistics.block_start) { - u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start; + u64 delta = rq_clock(rq_of(cfs_rq)) - se->statistics.block_start; if ((s64)delta < 0) delta = 0; @@ -1019,6 +2684,7 @@ static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se) if (unlikely(delta > se->statistics.block_max)) se->statistics.block_max = delta; + se->statistics.block_start = 0; se->statistics.sum_sleep_runtime += delta; if (tsk) { @@ -1088,9 +2754,7 @@ place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial) } /* ensure we never gain time by being placed backwards. */ - vruntime = max_vruntime(se->vruntime, vruntime); - - se->vruntime = vruntime; + se->vruntime = max_vruntime(se->vruntime, vruntime); } static void check_enqueue_throttle(struct cfs_rq *cfs_rq); @@ -1100,7 +2764,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) { /* * Update the normalized vruntime before updating min_vruntime - * through callig update_curr(). + * through calling update_curr(). */ if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING)) se->vruntime += cfs_rq->min_vruntime; @@ -1109,7 +2773,7 @@ enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) * Update run-time statistics of the 'current'. */ update_curr(cfs_rq); - update_cfs_load(cfs_rq, 0); + enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP); account_entity_enqueue(cfs_rq, se); update_cfs_shares(cfs_rq); @@ -1134,10 +2798,10 @@ static void __clear_buddies_last(struct sched_entity *se) { for_each_sched_entity(se) { struct cfs_rq *cfs_rq = cfs_rq_of(se); - if (cfs_rq->last == se) - cfs_rq->last = NULL; - else + if (cfs_rq->last != se) break; + + cfs_rq->last = NULL; } } @@ -1145,10 +2809,10 @@ static void __clear_buddies_next(struct sched_entity *se) { for_each_sched_entity(se) { struct cfs_rq *cfs_rq = cfs_rq_of(se); - if (cfs_rq->next == se) - cfs_rq->next = NULL; - else + if (cfs_rq->next != se) break; + + cfs_rq->next = NULL; } } @@ -1156,10 +2820,10 @@ static void __clear_buddies_skip(struct sched_entity *se) { for_each_sched_entity(se) { struct cfs_rq *cfs_rq = cfs_rq_of(se); - if (cfs_rq->skip == se) - cfs_rq->skip = NULL; - else + if (cfs_rq->skip != se) break; + + cfs_rq->skip = NULL; } } @@ -1175,7 +2839,7 @@ static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se) __clear_buddies_skip(se); } -static void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); +static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq); static void dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) @@ -1184,6 +2848,7 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) * Update run-time statistics of the 'current'. */ update_curr(cfs_rq); + dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP); update_stats_dequeue(cfs_rq, se); if (flags & DEQUEUE_SLEEP) { @@ -1192,9 +2857,9 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) struct task_struct *tsk = task_of(se); if (tsk->state & TASK_INTERRUPTIBLE) - se->statistics.sleep_start = rq_of(cfs_rq)->clock; + se->statistics.sleep_start = rq_clock(rq_of(cfs_rq)); if (tsk->state & TASK_UNINTERRUPTIBLE) - se->statistics.block_start = rq_of(cfs_rq)->clock; + se->statistics.block_start = rq_clock(rq_of(cfs_rq)); } #endif } @@ -1204,7 +2869,6 @@ dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags) if (se != cfs_rq->curr) __dequeue_entity(cfs_rq, se); se->on_rq = 0; - update_cfs_load(cfs_rq, 0); account_entity_dequeue(cfs_rq, se); /* @@ -1302,17 +2966,36 @@ wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se); * 3) pick the "last" process, for cache locality * 4) do not run the "skip" process, if something else is available */ -static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) +static struct sched_entity * +pick_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *curr) { - struct sched_entity *se = __pick_first_entity(cfs_rq); - struct sched_entity *left = se; + struct sched_entity *left = __pick_first_entity(cfs_rq); + struct sched_entity *se; + + /* + * If curr is set we have to see if its left of the leftmost entity + * still in the tree, provided there was anything in the tree at all. + */ + if (!left || (curr && entity_before(curr, left))) + left = curr; + + se = left; /* ideally we run the leftmost entity */ /* * Avoid running the skip buddy, if running something else can * be done without getting too unfair. */ if (cfs_rq->skip == se) { - struct sched_entity *second = __pick_next_entity(se); + struct sched_entity *second; + + if (se == curr) { + second = __pick_first_entity(cfs_rq); + } else { + second = __pick_next_entity(se); + if (!second || (curr && entity_before(curr, second))) + second = curr; + } + if (second && wakeup_preempt_entity(second, left) < 1) se = second; } @@ -1334,7 +3017,7 @@ static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq) return se; } -static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq); +static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq); static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) { @@ -1353,6 +3036,8 @@ static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev) update_stats_wait_start(cfs_rq, prev); /* Put 'current' back into the tree. */ __enqueue_entity(cfs_rq, prev); + /* in !on_rq case, update occurred at dequeue */ + update_entity_load_avg(prev, 1); } cfs_rq->curr = NULL; } @@ -1366,9 +3051,11 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) update_curr(cfs_rq); /* - * Update share accounting for long-running entities. + * Ensure that runnable average is periodically updated. */ - update_entity_shares_tick(cfs_rq); + update_entity_load_avg(curr, 1); + update_cfs_rq_blocked_load(cfs_rq, 1); + update_cfs_shares(cfs_rq); #ifdef CONFIG_SCHED_HRTICK /* @@ -1399,20 +3086,21 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued) #ifdef CONFIG_CFS_BANDWIDTH #ifdef HAVE_JUMP_LABEL -static struct jump_label_key __cfs_bandwidth_used; +static struct static_key __cfs_bandwidth_used; static inline bool cfs_bandwidth_used(void) { - return static_branch(&__cfs_bandwidth_used); + return static_key_false(&__cfs_bandwidth_used); +} + +void cfs_bandwidth_usage_inc(void) +{ + static_key_slow_inc(&__cfs_bandwidth_used); } -void account_cfs_bandwidth_used(int enabled, int was_enabled) +void cfs_bandwidth_usage_dec(void) { - /* only need to count groups transitioning between enabled/!enabled */ - if (enabled && !was_enabled) - jump_label_inc(&__cfs_bandwidth_used); - else if (!enabled && was_enabled) - jump_label_dec(&__cfs_bandwidth_used); + static_key_slow_dec(&__cfs_bandwidth_used); } #else /* HAVE_JUMP_LABEL */ static bool cfs_bandwidth_used(void) @@ -1420,7 +3108,8 @@ static bool cfs_bandwidth_used(void) return true; } -void account_cfs_bandwidth_used(int enabled, int was_enabled) {} +void cfs_bandwidth_usage_inc(void) {} +void cfs_bandwidth_usage_dec(void) {} #endif /* HAVE_JUMP_LABEL */ /* @@ -1461,6 +3150,15 @@ static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) return &tg->cfs_bandwidth; } +/* rq->task_clock normalized against any time this cfs_rq has spent throttled */ +static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) +{ + if (unlikely(cfs_rq->throttle_count)) + return cfs_rq->throttled_clock_task; + + return rq_clock_task(rq_of(cfs_rq)) - cfs_rq->throttled_clock_task_time; +} + /* returns 0 on failure to allocate runtime */ static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) { @@ -1483,7 +3181,7 @@ static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) */ if (!cfs_b->timer_active) { __refill_cfs_bandwidth_runtime(cfs_b); - __start_cfs_bandwidth(cfs_b); + __start_cfs_bandwidth(cfs_b, false); } if (cfs_b->runtime > 0) { @@ -1514,10 +3212,9 @@ static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq) static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq) { struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); - struct rq *rq = rq_of(cfs_rq); /* if the deadline is ahead of our clock, nothing to do */ - if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0)) + if (likely((s64)(rq_clock(rq_of(cfs_rq)) - cfs_rq->runtime_expires) < 0)) return; if (cfs_rq->runtime_remaining < 0) @@ -1529,10 +3226,12 @@ static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq) * has not truly expired. * * Fortunately we can check determine whether this the case by checking - * whether the global deadline has advanced. + * whether the global deadline has advanced. It is valid to compare + * cfs_b->runtime_expires without any locks since we only care about + * exact equality, so a partial write will still work. */ - if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) { + if (cfs_rq->runtime_expires != cfs_b->runtime_expires) { /* extend local deadline, drift is bounded above by 2 ticks */ cfs_rq->runtime_expires += TICK_NSEC; } else { @@ -1541,8 +3240,7 @@ static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq) } } -static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, - unsigned long delta_exec) +static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) { /* dock delta_exec before expiring quota (as it could span periods) */ cfs_rq->runtime_remaining -= delta_exec; @@ -1559,8 +3257,8 @@ static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq, resched_task(rq_of(cfs_rq)->curr); } -static __always_inline void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, - unsigned long delta_exec) +static __always_inline +void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) { if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled) return; @@ -1605,14 +3303,9 @@ static int tg_unthrottle_up(struct task_group *tg, void *data) cfs_rq->throttle_count--; #ifdef CONFIG_SMP if (!cfs_rq->throttle_count) { - u64 delta = rq->clock_task - cfs_rq->load_stamp; - - /* leaving throttled state, advance shares averaging windows */ - cfs_rq->load_stamp += delta; - cfs_rq->load_last += delta; - - /* update entity weight now that we are on_rq again */ - update_cfs_shares(cfs_rq); + /* adjust cfs_rq_clock_task() */ + cfs_rq->throttled_clock_task_time += rq_clock_task(rq) - + cfs_rq->throttled_clock_task; } #endif @@ -1624,9 +3317,9 @@ static int tg_throttle_down(struct task_group *tg, void *data) struct rq *rq = data; struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)]; - /* group is entering throttled state, record last load */ + /* group is entering throttled state, stop time */ if (!cfs_rq->throttle_count) - update_cfs_load(cfs_rq, 0); + cfs_rq->throttled_clock_task = rq_clock_task(rq); cfs_rq->throttle_count++; return 0; @@ -1641,7 +3334,7 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq) se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; - /* account load preceding throttle */ + /* freeze hierarchy runnable averages while throttled */ rcu_read_lock(); walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq); rcu_read_unlock(); @@ -1662,12 +3355,14 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq) } if (!se) - rq->nr_running -= task_delta; + sub_nr_running(rq, task_delta); cfs_rq->throttled = 1; - cfs_rq->throttled_timestamp = rq->clock; + cfs_rq->throttled_clock = rq_clock(rq); raw_spin_lock(&cfs_b->lock); list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq); + if (!cfs_b->timer_active) + __start_cfs_bandwidth(cfs_b, false); raw_spin_unlock(&cfs_b->lock); } @@ -1679,16 +3374,17 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) int enqueue = 1; long task_delta; - se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))]; + se = cfs_rq->tg->se[cpu_of(rq)]; cfs_rq->throttled = 0; + + update_rq_clock(rq); + raw_spin_lock(&cfs_b->lock); - cfs_b->throttled_time += rq->clock - cfs_rq->throttled_timestamp; + cfs_b->throttled_time += rq_clock(rq) - cfs_rq->throttled_clock; list_del_rcu(&cfs_rq->throttled_list); raw_spin_unlock(&cfs_b->lock); - cfs_rq->throttled_timestamp = 0; - update_rq_clock(rq); /* update hierarchical throttle state */ walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq); @@ -1710,7 +3406,7 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) } if (!se) - rq->nr_running += task_delta; + add_nr_running(rq, task_delta); /* determine whether we need to wake up potentially idle cpu */ if (rq->curr == rq->idle && rq->cfs.nr_running) @@ -1764,28 +3460,35 @@ next: static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) { u64 runtime, runtime_expires; - int idle = 1, throttled; + int throttled; - raw_spin_lock(&cfs_b->lock); /* no need to continue the timer with no bandwidth constraint */ if (cfs_b->quota == RUNTIME_INF) - goto out_unlock; + goto out_deactivate; throttled = !list_empty(&cfs_b->throttled_cfs_rq); - /* idle depends on !throttled (for the case of a large deficit) */ - idle = cfs_b->idle && !throttled; cfs_b->nr_periods += overrun; - /* if we're going inactive then everything else can be deferred */ - if (idle) - goto out_unlock; + /* + * idle depends on !throttled (for the case of a large deficit), and if + * we're going inactive then everything else can be deferred + */ + if (cfs_b->idle && !throttled) + goto out_deactivate; + + /* + * if we have relooped after returning idle once, we need to update our + * status as actually running, so that other cpus doing + * __start_cfs_bandwidth will stop trying to cancel us. + */ + cfs_b->timer_active = 1; __refill_cfs_bandwidth_runtime(cfs_b); if (!throttled) { /* mark as potentially idle for the upcoming period */ cfs_b->idle = 1; - goto out_unlock; + return 0; } /* account preceding periods in which throttling occurred */ @@ -1825,12 +3528,12 @@ static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) * timer to remain active while there are any throttled entities.) */ cfs_b->idle = 0; -out_unlock: - if (idle) - cfs_b->timer_active = 0; - raw_spin_unlock(&cfs_b->lock); - return idle; + return 0; + +out_deactivate: + cfs_b->timer_active = 0; + return 1; } /* a cfs_rq won't donate quota below this amount */ @@ -1840,7 +3543,13 @@ static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC; /* how long we wait to gather additional slack before distributing */ static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC; -/* are we near the end of the current quota period? */ +/* + * Are we near the end of the current quota period? + * + * Requires cfs_b->lock for hrtimer_expires_remaining to be safe against the + * hrtimer base being cleared by __hrtimer_start_range_ns. In the case of + * migrate_hrtimers, base is never cleared, so we are fine. + */ static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire) { struct hrtimer *refresh_timer = &cfs_b->period_timer; @@ -1916,10 +3625,12 @@ static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b) u64 expires; /* confirm we're still not at a refresh boundary */ - if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) + raw_spin_lock(&cfs_b->lock); + if (runtime_refresh_within(cfs_b, min_bandwidth_expiration)) { + raw_spin_unlock(&cfs_b->lock); return; + } - raw_spin_lock(&cfs_b->lock); if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) { runtime = cfs_b->runtime; cfs_b->runtime = 0; @@ -1963,28 +3674,25 @@ static void check_enqueue_throttle(struct cfs_rq *cfs_rq) } /* conditionally throttle active cfs_rq's from put_prev_entity() */ -static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) +static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { if (!cfs_bandwidth_used()) - return; + return false; if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0)) - return; + return false; /* * it's possible for a throttled entity to be forced into a running * state (e.g. set_curr_task), in this case we're finished. */ if (cfs_rq_throttled(cfs_rq)) - return; + return true; throttle_cfs_rq(cfs_rq); + return true; } -static inline u64 default_cfs_period(void); -static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun); -static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b); - static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer) { struct cfs_bandwidth *cfs_b = @@ -2002,6 +3710,7 @@ static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) int overrun; int idle = 0; + raw_spin_lock(&cfs_b->lock); for (;;) { now = hrtimer_cb_get_time(timer); overrun = hrtimer_forward(timer, now, cfs_b->period); @@ -2011,6 +3720,7 @@ static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer) idle = do_sched_cfs_period_timer(cfs_b, overrun); } + raw_spin_unlock(&cfs_b->lock); return idle ? HRTIMER_NORESTART : HRTIMER_RESTART; } @@ -2036,7 +3746,7 @@ static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) } /* requires cfs_b->lock, may release to reprogram timer */ -void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b) +void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b, bool force) { /* * The timer may be active because we're trying to set a new bandwidth @@ -2044,14 +3754,14 @@ void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b) * (timer_active==0 becomes visible before the hrtimer call-back * terminates). In either case we ensure that it's re-programmed */ - while (unlikely(hrtimer_active(&cfs_b->period_timer))) { + while (unlikely(hrtimer_active(&cfs_b->period_timer)) && + hrtimer_try_to_cancel(&cfs_b->period_timer) < 0) { + /* bounce the lock to allow do_sched_cfs_period_timer to run */ raw_spin_unlock(&cfs_b->lock); - /* ensure cfs_b->lock is available while we wait */ - hrtimer_cancel(&cfs_b->period_timer); - + cpu_relax(); raw_spin_lock(&cfs_b->lock); /* if someone else restarted the timer then we're done */ - if (cfs_b->timer_active) + if (!force && cfs_b->timer_active) return; } @@ -2065,13 +3775,11 @@ static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) hrtimer_cancel(&cfs_b->slack_timer); } -void unthrottle_offline_cfs_rqs(struct rq *rq) +static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq) { struct cfs_rq *cfs_rq; for_each_leaf_cfs_rq(rq, cfs_rq) { - struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg); - if (!cfs_rq->runtime_enabled) continue; @@ -2079,18 +3787,22 @@ void unthrottle_offline_cfs_rqs(struct rq *rq) * clock_task is not advancing so we just need to make sure * there's some valid quota amount */ - cfs_rq->runtime_remaining = cfs_b->quota; + cfs_rq->runtime_remaining = 1; if (cfs_rq_throttled(cfs_rq)) unthrottle_cfs_rq(cfs_rq); } } #else /* CONFIG_CFS_BANDWIDTH */ -static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, - unsigned long delta_exec) {} -static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} +static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) +{ + return rq_clock_task(rq_of(cfs_rq)); +} + +static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {} +static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; } static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {} -static void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} +static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq) { @@ -2119,7 +3831,7 @@ static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg) return NULL; } static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {} -void unthrottle_offline_cfs_rqs(struct rq *rq) {} +static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {} #endif /* CONFIG_CFS_BANDWIDTH */ @@ -2220,12 +3932,14 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) if (cfs_rq_throttled(cfs_rq)) break; - update_cfs_load(cfs_rq, 0); update_cfs_shares(cfs_rq); + update_entity_load_avg(se, 1); } - if (!se) - inc_nr_running(rq); + if (!se) { + update_rq_runnable_avg(rq, rq->nr_running); + add_nr_running(rq, 1); + } hrtick_update(rq); } @@ -2279,12 +3993,14 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) if (cfs_rq_throttled(cfs_rq)) break; - update_cfs_load(cfs_rq, 0); update_cfs_shares(cfs_rq); + update_entity_load_avg(se, 1); } - if (!se) - dec_nr_running(rq); + if (!se) { + sub_nr_running(rq, 1); + update_rq_runnable_avg(rq, 1); + } hrtick_update(rq); } @@ -2292,7 +4008,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) /* Used instead of source_load when we know the type == 0 */ static unsigned long weighted_cpuload(const int cpu) { - return cpu_rq(cpu)->load.weight; + return cpu_rq(cpu)->cfs.runnable_load_avg; } /* @@ -2328,22 +4044,40 @@ static unsigned long target_load(int cpu, int type) return max(rq->cpu_load[type-1], total); } -static unsigned long power_of(int cpu) +static unsigned long capacity_of(int cpu) { - return cpu_rq(cpu)->cpu_power; + return cpu_rq(cpu)->cpu_capacity; } static unsigned long cpu_avg_load_per_task(int cpu) { struct rq *rq = cpu_rq(cpu); unsigned long nr_running = ACCESS_ONCE(rq->nr_running); + unsigned long load_avg = rq->cfs.runnable_load_avg; if (nr_running) - return rq->load.weight / nr_running; + return load_avg / nr_running; return 0; } +static void record_wakee(struct task_struct *p) +{ + /* + * Rough decay (wiping) for cost saving, don't worry + * about the boundary, really active task won't care + * about the loss. + */ + if (time_after(jiffies, current->wakee_flip_decay_ts + HZ)) { + current->wakee_flips >>= 1; + current->wakee_flip_decay_ts = jiffies; + } + + if (current->last_wakee != p) { + current->last_wakee = p; + current->wakee_flips++; + } +} static void task_waking_fair(struct task_struct *p) { @@ -2364,6 +4098,7 @@ static void task_waking_fair(struct task_struct *p) #endif se->vruntime -= min_vruntime; + record_wakee(p); } #ifdef CONFIG_FAIR_GROUP_SCHED @@ -2474,14 +4209,35 @@ static long effective_load(struct task_group *tg, int cpu, long wl, long wg) } #else -static inline unsigned long effective_load(struct task_group *tg, int cpu, - unsigned long wl, unsigned long wg) +static long effective_load(struct task_group *tg, int cpu, long wl, long wg) { return wl; } #endif +static int wake_wide(struct task_struct *p) +{ + int factor = this_cpu_read(sd_llc_size); + + /* + * Yeah, it's the switching-frequency, could means many wakee or + * rapidly switch, use factor here will just help to automatically + * adjust the loose-degree, so bigger node will lead to more pull. + */ + if (p->wakee_flips > factor) { + /* + * wakee is somewhat hot, it needs certain amount of cpu + * resource, so if waker is far more hot, prefer to leave + * it alone. + */ + if (current->wakee_flips > (factor * p->wakee_flips)) + return 1; + } + + return 0; +} + static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) { s64 this_load, load; @@ -2491,6 +4247,13 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) unsigned long weight; int balanced; + /* + * If we wake multiple tasks be careful to not bounce + * ourselves around too much. + */ + if (wake_wide(p)) + return 0; + idx = sd->wake_idx; this_cpu = smp_processor_id(); prev_cpu = task_cpu(p); @@ -2526,12 +4289,12 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) s64 this_eff_load, prev_eff_load; this_eff_load = 100; - this_eff_load *= power_of(prev_cpu); + this_eff_load *= capacity_of(prev_cpu); this_eff_load *= this_load + effective_load(tg, this_cpu, weight, weight); prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2; - prev_eff_load *= power_of(this_cpu); + prev_eff_load *= capacity_of(this_cpu); prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight); balanced = this_eff_load <= prev_eff_load; @@ -2571,12 +4334,16 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync) */ static struct sched_group * find_idlest_group(struct sched_domain *sd, struct task_struct *p, - int this_cpu, int load_idx) + int this_cpu, int sd_flag) { struct sched_group *idlest = NULL, *group = sd->groups; unsigned long min_load = ULONG_MAX, this_load = 0; + int load_idx = sd->forkexec_idx; int imbalance = 100 + (sd->imbalance_pct-100)/2; + if (sd_flag & SD_BALANCE_WAKE) + load_idx = sd->wake_idx; + do { unsigned long load, avg_load; int local_group; @@ -2603,8 +4370,8 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p, avg_load += load; } - /* Adjust by relative CPU power of the group */ - avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power; + /* Adjust by relative CPU capacity of the group */ + avg_load = (avg_load * SCHED_CAPACITY_SCALE) / group->sgc->capacity; if (local_group) { this_load = avg_load; @@ -2647,31 +4414,22 @@ find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu) */ static int select_idle_sibling(struct task_struct *p, int target) { - int cpu = smp_processor_id(); - int prev_cpu = task_cpu(p); struct sched_domain *sd; struct sched_group *sg; - int i; + int i = task_cpu(p); - /* - * If the task is going to be woken-up on this cpu and if it is - * already idle, then it is the right target. - */ - if (target == cpu && idle_cpu(cpu)) - return cpu; + if (idle_cpu(target)) + return target; /* - * If the task is going to be woken-up on the cpu where it previously - * ran and if it is currently idle, then it the right target. + * If the prevous cpu is cache affine and idle, don't be stupid. */ - if (target == prev_cpu && idle_cpu(prev_cpu)) - return prev_cpu; + if (i != target && cpus_share_cache(i, target) && idle_cpu(i)) + return i; /* * Otherwise, iterate the domains and find an elegible idle cpu. */ - rcu_read_lock(); - sd = rcu_dereference(per_cpu(sd_llc, target)); for_each_lower_domain(sd) { sg = sd->groups; @@ -2681,7 +4439,7 @@ static int select_idle_sibling(struct task_struct *p, int target) goto next; for_each_cpu(i, sched_group_cpus(sg)) { - if (!idle_cpu(i)) + if (i == target || !idle_cpu(i)) goto next; } @@ -2693,34 +4451,31 @@ next: } while (sg != sd->groups); } done: - rcu_read_unlock(); - return target; } /* - * sched_balance_self: balance the current task (running on cpu) in domains - * that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and - * SD_BALANCE_EXEC. + * select_task_rq_fair: Select target runqueue for the waking task in domains + * that have the 'sd_flag' flag set. In practice, this is SD_BALANCE_WAKE, + * SD_BALANCE_FORK, or SD_BALANCE_EXEC. * - * Balance, ie. select the least loaded group. + * Balances load by selecting the idlest cpu in the idlest group, or under + * certain conditions an idle sibling cpu if the domain has SD_WAKE_AFFINE set. * - * Returns the target CPU number, or the same CPU if no balancing is needed. + * Returns the target cpu number. * * preempt must be disabled. */ static int -select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags) +select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_flags) { struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL; int cpu = smp_processor_id(); - int prev_cpu = task_cpu(p); int new_cpu = cpu; int want_affine = 0; - int want_sd = 1; int sync = wake_flags & WF_SYNC; - if (p->rt.nr_cpus_allowed == 1) + if (p->nr_cpus_allowed == 1) return prev_cpu; if (sd_flag & SD_BALANCE_WAKE) { @@ -2735,59 +4490,28 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags) continue; /* - * If power savings logic is enabled for a domain, see if we - * are not overloaded, if so, don't balance wider. - */ - if (tmp->flags & (SD_POWERSAVINGS_BALANCE|SD_PREFER_LOCAL)) { - unsigned long power = 0; - unsigned long nr_running = 0; - unsigned long capacity; - int i; - - for_each_cpu(i, sched_domain_span(tmp)) { - power += power_of(i); - nr_running += cpu_rq(i)->cfs.nr_running; - } - - capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE); - - if (tmp->flags & SD_POWERSAVINGS_BALANCE) - nr_running /= 2; - - if (nr_running < capacity) - want_sd = 0; - } - - /* * If both cpu and prev_cpu are part of this domain, * cpu is a valid SD_WAKE_AFFINE target. */ if (want_affine && (tmp->flags & SD_WAKE_AFFINE) && cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) { affine_sd = tmp; - want_affine = 0; - } - - if (!want_sd && !want_affine) break; + } - if (!(tmp->flags & sd_flag)) - continue; - - if (want_sd) + if (tmp->flags & sd_flag) sd = tmp; } - if (affine_sd) { - if (cpu == prev_cpu || wake_affine(affine_sd, p, sync)) - prev_cpu = cpu; + if (affine_sd && cpu != prev_cpu && wake_affine(affine_sd, p, sync)) + prev_cpu = cpu; + if (sd_flag & SD_BALANCE_WAKE) { new_cpu = select_idle_sibling(p, prev_cpu); goto unlock; } while (sd) { - int load_idx = sd->forkexec_idx; struct sched_group *group; int weight; @@ -2796,10 +4520,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags) continue; } - if (sd_flag & SD_BALANCE_WAKE) - load_idx = sd->wake_idx; - - group = find_idlest_group(sd, p, cpu, load_idx); + group = find_idlest_group(sd, p, cpu, sd_flag); if (!group) { sd = sd->child; continue; @@ -2829,6 +4550,34 @@ unlock: return new_cpu; } + +/* + * Called immediately before a task is migrated to a new cpu; task_cpu(p) and + * cfs_rq_of(p) references at time of call are still valid and identify the + * previous cpu. However, the caller only guarantees p->pi_lock is held; no + * other assumptions, including the state of rq->lock, should be made. + */ +static void +migrate_task_rq_fair(struct task_struct *p, int next_cpu) +{ + struct sched_entity *se = &p->se; + struct cfs_rq *cfs_rq = cfs_rq_of(se); + + /* + * Load tracking: accumulate removed load so that it can be processed + * when we next update owning cfs_rq under rq->lock. Tasks contribute + * to blocked load iff they have a positive decay-count. It can never + * be negative here since on-rq tasks have decay-count == 0. + */ + if (se->avg.decay_count) { + se->avg.decay_count = -__synchronize_entity_decay(se); + atomic_long_add(se->avg.load_avg_contrib, + &cfs_rq->removed_load); + } + + /* We have migrated, no longer consider this task hot */ + se->exec_start = 0; +} #endif /* CONFIG_SMP */ static unsigned long @@ -2920,7 +4669,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ return; /* - * This is possible from callers such as pull_task(), in which we + * This is possible from callers such as move_task(), in which we * unconditionally check_prempt_curr() after an enqueue (which may have * lead to a throttle). This both saves work and prevents false * next-buddy nomination below. @@ -2955,7 +4704,7 @@ static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_ * Batch and idle tasks do not preempt non-idle tasks (their preemption * is driven by the tick): */ - if (unlikely(p->policy != SCHED_NORMAL)) + if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION)) return; find_matching_se(&se, &pse); @@ -2991,26 +4740,124 @@ preempt: set_last_buddy(se); } -static struct task_struct *pick_next_task_fair(struct rq *rq) +static struct task_struct * +pick_next_task_fair(struct rq *rq, struct task_struct *prev) { - struct task_struct *p; struct cfs_rq *cfs_rq = &rq->cfs; struct sched_entity *se; + struct task_struct *p; + int new_tasks; +again: +#ifdef CONFIG_FAIR_GROUP_SCHED if (!cfs_rq->nr_running) - return NULL; + goto idle; + + if (prev->sched_class != &fair_sched_class) + goto simple; + + /* + * Because of the set_next_buddy() in dequeue_task_fair() it is rather + * likely that a next task is from the same cgroup as the current. + * + * Therefore attempt to avoid putting and setting the entire cgroup + * hierarchy, only change the part that actually changes. + */ + + do { + struct sched_entity *curr = cfs_rq->curr; + + /* + * Since we got here without doing put_prev_entity() we also + * have to consider cfs_rq->curr. If it is still a runnable + * entity, update_curr() will update its vruntime, otherwise + * forget we've ever seen it. + */ + if (curr && curr->on_rq) + update_curr(cfs_rq); + else + curr = NULL; + + /* + * This call to check_cfs_rq_runtime() will do the throttle and + * dequeue its entity in the parent(s). Therefore the 'simple' + * nr_running test will indeed be correct. + */ + if (unlikely(check_cfs_rq_runtime(cfs_rq))) + goto simple; + + se = pick_next_entity(cfs_rq, curr); + cfs_rq = group_cfs_rq(se); + } while (cfs_rq); + + p = task_of(se); + + /* + * Since we haven't yet done put_prev_entity and if the selected task + * is a different task than we started out with, try and touch the + * least amount of cfs_rqs. + */ + if (prev != p) { + struct sched_entity *pse = &prev->se; + + while (!(cfs_rq = is_same_group(se, pse))) { + int se_depth = se->depth; + int pse_depth = pse->depth; + + if (se_depth <= pse_depth) { + put_prev_entity(cfs_rq_of(pse), pse); + pse = parent_entity(pse); + } + if (se_depth >= pse_depth) { + set_next_entity(cfs_rq_of(se), se); + se = parent_entity(se); + } + } + + put_prev_entity(cfs_rq, pse); + set_next_entity(cfs_rq, se); + } + + if (hrtick_enabled(rq)) + hrtick_start_fair(rq, p); + + return p; +simple: + cfs_rq = &rq->cfs; +#endif + + if (!cfs_rq->nr_running) + goto idle; + + put_prev_task(rq, prev); do { - se = pick_next_entity(cfs_rq); + se = pick_next_entity(cfs_rq, NULL); set_next_entity(cfs_rq, se); cfs_rq = group_cfs_rq(se); } while (cfs_rq); p = task_of(se); + if (hrtick_enabled(rq)) hrtick_start_fair(rq, p); return p; + +idle: + new_tasks = idle_balance(rq); + /* + * Because idle_balance() releases (and re-acquires) rq->lock, it is + * possible for any higher priority task to appear. In that case we + * must re-start the pick_next_entity() loop. + */ + if (new_tasks < 0) + return RETRY_TASK; + + if (new_tasks > 0) + goto again; + + return NULL; } /* @@ -3081,27 +4928,174 @@ static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preemp #ifdef CONFIG_SMP /************************************************** - * Fair scheduling class load-balancing methods: - */ + * Fair scheduling class load-balancing methods. + * + * BASICS + * + * The purpose of load-balancing is to achieve the same basic fairness the + * per-cpu scheduler provides, namely provide a proportional amount of compute + * time to each task. This is expressed in the following equation: + * + * W_i,n/P_i == W_j,n/P_j for all i,j (1) + * + * Where W_i,n is the n-th weight average for cpu i. The instantaneous weight + * W_i,0 is defined as: + * + * W_i,0 = \Sum_j w_i,j (2) + * + * Where w_i,j is the weight of the j-th runnable task on cpu i. This weight + * is derived from the nice value as per prio_to_weight[]. + * + * The weight average is an exponential decay average of the instantaneous + * weight: + * + * W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3) + * + * C_i is the compute capacity of cpu i, typically it is the + * fraction of 'recent' time available for SCHED_OTHER task execution. But it + * can also include other factors [XXX]. + * + * To achieve this balance we define a measure of imbalance which follows + * directly from (1): + * + * imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j } (4) + * + * We them move tasks around to minimize the imbalance. In the continuous + * function space it is obvious this converges, in the discrete case we get + * a few fun cases generally called infeasible weight scenarios. + * + * [XXX expand on: + * - infeasible weights; + * - local vs global optima in the discrete case. ] + * + * + * SCHED DOMAINS + * + * In order to solve the imbalance equation (4), and avoid the obvious O(n^2) + * for all i,j solution, we create a tree of cpus that follows the hardware + * topology where each level pairs two lower groups (or better). This results + * in O(log n) layers. Furthermore we reduce the number of cpus going up the + * tree to only the first of the previous level and we decrease the frequency + * of load-balance at each level inv. proportional to the number of cpus in + * the groups. + * + * This yields: + * + * log_2 n 1 n + * \Sum { --- * --- * 2^i } = O(n) (5) + * i = 0 2^i 2^i + * `- size of each group + * | | `- number of cpus doing load-balance + * | `- freq + * `- sum over all levels + * + * Coupled with a limit on how many tasks we can migrate every balance pass, + * this makes (5) the runtime complexity of the balancer. + * + * An important property here is that each CPU is still (indirectly) connected + * to every other cpu in at most O(log n) steps: + * + * The adjacency matrix of the resulting graph is given by: + * + * log_2 n + * A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6) + * k = 0 + * + * And you'll find that: + * + * A^(log_2 n)_i,j != 0 for all i,j (7) + * + * Showing there's indeed a path between every cpu in at most O(log n) steps. + * The task movement gives a factor of O(m), giving a convergence complexity + * of: + * + * O(nm log n), n := nr_cpus, m := nr_tasks (8) + * + * + * WORK CONSERVING + * + * In order to avoid CPUs going idle while there's still work to do, new idle + * balancing is more aggressive and has the newly idle cpu iterate up the domain + * tree itself instead of relying on other CPUs to bring it work. + * + * This adds some complexity to both (5) and (8) but it reduces the total idle + * time. + * + * [XXX more?] + * + * + * CGROUPS + * + * Cgroups make a horror show out of (2), instead of a simple sum we get: + * + * s_k,i + * W_i,0 = \Sum_j \Prod_k w_k * ----- (9) + * S_k + * + * Where + * + * s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10) + * + * w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i. + * + * The big problem is S_k, its a global sum needed to compute a local (W_i) + * property. + * + * [XXX write more on how we solve this.. _after_ merging pjt's patches that + * rewrite all of this once again.] + */ + +static unsigned long __read_mostly max_load_balance_interval = HZ/10; + +enum fbq_type { regular, remote, all }; + +#define LBF_ALL_PINNED 0x01 +#define LBF_NEED_BREAK 0x02 +#define LBF_DST_PINNED 0x04 +#define LBF_SOME_PINNED 0x08 + +struct lb_env { + struct sched_domain *sd; + + struct rq *src_rq; + int src_cpu; + + int dst_cpu; + struct rq *dst_rq; + + struct cpumask *dst_grpmask; + int new_dst_cpu; + enum cpu_idle_type idle; + long imbalance; + /* The set of CPUs under consideration for load-balancing */ + struct cpumask *cpus; + + unsigned int flags; + + unsigned int loop; + unsigned int loop_break; + unsigned int loop_max; + + enum fbq_type fbq_type; +}; /* - * pull_task - move a task from a remote runqueue to the local runqueue. + * move_task - move a task from one runqueue to another runqueue. * Both runqueues must be locked. */ -static void pull_task(struct rq *src_rq, struct task_struct *p, - struct rq *this_rq, int this_cpu) +static void move_task(struct task_struct *p, struct lb_env *env) { - deactivate_task(src_rq, p, 0); - set_task_cpu(p, this_cpu); - activate_task(this_rq, p, 0); - check_preempt_curr(this_rq, p, 0); + deactivate_task(env->src_rq, p, 0); + set_task_cpu(p, env->dst_cpu); + activate_task(env->dst_rq, p, 0); + check_preempt_curr(env->dst_rq, p, 0); } /* * Is this task likely cache-hot: */ static int -task_hot(struct task_struct *p, u64 now, struct sched_domain *sd) +task_hot(struct task_struct *p, u64 now) { s64 delta; @@ -3129,61 +5123,182 @@ task_hot(struct task_struct *p, u64 now, struct sched_domain *sd) return delta < (s64)sysctl_sched_migration_cost; } -#define LBF_ALL_PINNED 0x01 -#define LBF_NEED_BREAK 0x02 /* clears into HAD_BREAK */ -#define LBF_HAD_BREAK 0x04 -#define LBF_HAD_BREAKS 0x0C /* count HAD_BREAKs overflows into ABORT */ -#define LBF_ABORT 0x10 +#ifdef CONFIG_NUMA_BALANCING +/* Returns true if the destination node has incurred more faults */ +static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env) +{ + struct numa_group *numa_group = rcu_dereference(p->numa_group); + int src_nid, dst_nid; + + if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults_memory || + !(env->sd->flags & SD_NUMA)) { + return false; + } + + src_nid = cpu_to_node(env->src_cpu); + dst_nid = cpu_to_node(env->dst_cpu); + + if (src_nid == dst_nid) + return false; + + if (numa_group) { + /* Task is already in the group's interleave set. */ + if (node_isset(src_nid, numa_group->active_nodes)) + return false; + + /* Task is moving into the group's interleave set. */ + if (node_isset(dst_nid, numa_group->active_nodes)) + return true; + + return group_faults(p, dst_nid) > group_faults(p, src_nid); + } + + /* Encourage migration to the preferred node. */ + if (dst_nid == p->numa_preferred_nid) + return true; + + return task_faults(p, dst_nid) > task_faults(p, src_nid); +} + + +static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env) +{ + struct numa_group *numa_group = rcu_dereference(p->numa_group); + int src_nid, dst_nid; + + if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER)) + return false; + + if (!p->numa_faults_memory || !(env->sd->flags & SD_NUMA)) + return false; + + src_nid = cpu_to_node(env->src_cpu); + dst_nid = cpu_to_node(env->dst_cpu); + + if (src_nid == dst_nid) + return false; + + if (numa_group) { + /* Task is moving within/into the group's interleave set. */ + if (node_isset(dst_nid, numa_group->active_nodes)) + return false; + + /* Task is moving out of the group's interleave set. */ + if (node_isset(src_nid, numa_group->active_nodes)) + return true; + + return group_faults(p, dst_nid) < group_faults(p, src_nid); + } + + /* Migrating away from the preferred node is always bad. */ + if (src_nid == p->numa_preferred_nid) + return true; + + return task_faults(p, dst_nid) < task_faults(p, src_nid); +} + +#else +static inline bool migrate_improves_locality(struct task_struct *p, + struct lb_env *env) +{ + return false; +} + +static inline bool migrate_degrades_locality(struct task_struct *p, + struct lb_env *env) +{ + return false; +} +#endif /* * can_migrate_task - may task p from runqueue rq be migrated to this_cpu? */ static -int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu, - struct sched_domain *sd, enum cpu_idle_type idle, - int *lb_flags) +int can_migrate_task(struct task_struct *p, struct lb_env *env) { int tsk_cache_hot = 0; /* * We do not migrate tasks that are: - * 1) running (obviously), or + * 1) throttled_lb_pair, or * 2) cannot be migrated to this CPU due to cpus_allowed, or - * 3) are cache-hot on their current CPU. + * 3) running (obviously), or + * 4) are cache-hot on their current CPU. */ - if (!cpumask_test_cpu(this_cpu, tsk_cpus_allowed(p))) { + if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu)) + return 0; + + if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) { + int cpu; + schedstat_inc(p, se.statistics.nr_failed_migrations_affine); + + env->flags |= LBF_SOME_PINNED; + + /* + * Remember if this task can be migrated to any other cpu in + * our sched_group. We may want to revisit it if we couldn't + * meet load balance goals by pulling other tasks on src_cpu. + * + * Also avoid computing new_dst_cpu if we have already computed + * one in current iteration. + */ + if (!env->dst_grpmask || (env->flags & LBF_DST_PINNED)) + return 0; + + /* Prevent to re-select dst_cpu via env's cpus */ + for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) { + if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) { + env->flags |= LBF_DST_PINNED; + env->new_dst_cpu = cpu; + break; + } + } + return 0; } - *lb_flags &= ~LBF_ALL_PINNED; - if (task_running(rq, p)) { + /* Record that we found atleast one task that could run on dst_cpu */ + env->flags &= ~LBF_ALL_PINNED; + + if (task_running(env->src_rq, p)) { schedstat_inc(p, se.statistics.nr_failed_migrations_running); return 0; } /* * Aggressive migration if: - * 1) task is cache cold, or - * 2) too many balance attempts have failed. + * 1) destination numa is preferred + * 2) task is cache cold, or + * 3) too many balance attempts have failed. */ + tsk_cache_hot = task_hot(p, rq_clock_task(env->src_rq)); + if (!tsk_cache_hot) + tsk_cache_hot = migrate_degrades_locality(p, env); - tsk_cache_hot = task_hot(p, rq->clock_task, sd); - if (!tsk_cache_hot || - sd->nr_balance_failed > sd->cache_nice_tries) { + if (migrate_improves_locality(p, env)) { #ifdef CONFIG_SCHEDSTATS if (tsk_cache_hot) { - schedstat_inc(sd, lb_hot_gained[idle]); + schedstat_inc(env->sd, lb_hot_gained[env->idle]); schedstat_inc(p, se.statistics.nr_forced_migrations); } #endif return 1; } - if (tsk_cache_hot) { - schedstat_inc(p, se.statistics.nr_failed_migrations_hot); - return 0; + if (!tsk_cache_hot || + env->sd->nr_balance_failed > env->sd->cache_nice_tries) { + + if (tsk_cache_hot) { + schedstat_inc(env->sd, lb_hot_gained[env->idle]); + schedstat_inc(p, se.statistics.nr_forced_migrations); + } + + return 1; } - return 1; + + schedstat_inc(p, se.statistics.nr_failed_migrations_hot); + return 0; } /* @@ -3193,65 +5308,74 @@ int can_migrate_task(struct task_struct *p, struct rq *rq, int this_cpu, * * Called with both runqueues locked. */ -static int -move_one_task(struct rq *this_rq, int this_cpu, struct rq *busiest, - struct sched_domain *sd, enum cpu_idle_type idle) +static int move_one_task(struct lb_env *env) { struct task_struct *p, *n; - struct cfs_rq *cfs_rq; - int pinned = 0; - for_each_leaf_cfs_rq(busiest, cfs_rq) { - list_for_each_entry_safe(p, n, &cfs_rq->tasks, se.group_node) { - if (throttled_lb_pair(task_group(p), - busiest->cpu, this_cpu)) - break; - - if (!can_migrate_task(p, busiest, this_cpu, - sd, idle, &pinned)) - continue; + list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) { + if (!can_migrate_task(p, env)) + continue; - pull_task(busiest, p, this_rq, this_cpu); - /* - * Right now, this is only the second place pull_task() - * is called, so we can safely collect pull_task() - * stats here rather than inside pull_task(). - */ - schedstat_inc(sd, lb_gained[idle]); - return 1; - } + move_task(p, env); + /* + * Right now, this is only the second place move_task() + * is called, so we can safely collect move_task() + * stats here rather than inside move_task(). + */ + schedstat_inc(env->sd, lb_gained[env->idle]); + return 1; } - return 0; } -static unsigned long -balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest, - unsigned long max_load_move, struct sched_domain *sd, - enum cpu_idle_type idle, int *lb_flags, - struct cfs_rq *busiest_cfs_rq) +static const unsigned int sched_nr_migrate_break = 32; + +/* + * move_tasks tries to move up to imbalance weighted load from busiest to + * this_rq, as part of a balancing operation within domain "sd". + * Returns 1 if successful and 0 otherwise. + * + * Called with both runqueues locked. + */ +static int move_tasks(struct lb_env *env) { - int loops = 0, pulled = 0; - long rem_load_move = max_load_move; - struct task_struct *p, *n; + struct list_head *tasks = &env->src_rq->cfs_tasks; + struct task_struct *p; + unsigned long load; + int pulled = 0; - if (max_load_move == 0) - goto out; + if (env->imbalance <= 0) + return 0; + + while (!list_empty(tasks)) { + p = list_first_entry(tasks, struct task_struct, se.group_node); - list_for_each_entry_safe(p, n, &busiest_cfs_rq->tasks, se.group_node) { - if (loops++ > sysctl_sched_nr_migrate) { - *lb_flags |= LBF_NEED_BREAK; + env->loop++; + /* We've more or less seen every task there is, call it quits */ + if (env->loop > env->loop_max) + break; + + /* take a breather every nr_migrate tasks */ + if (env->loop > env->loop_break) { + env->loop_break += sched_nr_migrate_break; + env->flags |= LBF_NEED_BREAK; break; } - if ((p->se.load.weight >> 1) > rem_load_move || - !can_migrate_task(p, busiest, this_cpu, sd, idle, - lb_flags)) - continue; + if (!can_migrate_task(p, env)) + goto next; + + load = task_h_load(p); + + if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed) + goto next; - pull_task(busiest, p, this_rq, this_cpu); + if ((load / 2) > env->imbalance) + goto next; + + move_task(p, env); pulled++; - rem_load_move -= p->se.load.weight; + env->imbalance -= load; #ifdef CONFIG_PREEMPT /* @@ -3259,273 +5383,209 @@ balance_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest, * kernels will stop after the first task is pulled to minimize * the critical section. */ - if (idle == CPU_NEWLY_IDLE) { - *lb_flags |= LBF_ABORT; + if (env->idle == CPU_NEWLY_IDLE) break; - } #endif /* * We only want to steal up to the prescribed amount of * weighted load. */ - if (rem_load_move <= 0) + if (env->imbalance <= 0) break; + + continue; +next: + list_move_tail(&p->se.group_node, tasks); } -out: + /* - * Right now, this is one of only two places pull_task() is called, - * so we can safely collect pull_task() stats here rather than - * inside pull_task(). + * Right now, this is one of only two places move_task() is called, + * so we can safely collect move_task() stats here rather than + * inside move_task(). */ - schedstat_add(sd, lb_gained[idle], pulled); + schedstat_add(env->sd, lb_gained[env->idle], pulled); - return max_load_move - rem_load_move; + return pulled; } #ifdef CONFIG_FAIR_GROUP_SCHED /* * update tg->load_weight by folding this cpu's load_avg */ -static int update_shares_cpu(struct task_group *tg, int cpu) +static void __update_blocked_averages_cpu(struct task_group *tg, int cpu) { - struct cfs_rq *cfs_rq; - unsigned long flags; - struct rq *rq; - - if (!tg->se[cpu]) - return 0; - - rq = cpu_rq(cpu); - cfs_rq = tg->cfs_rq[cpu]; - - raw_spin_lock_irqsave(&rq->lock, flags); - - update_rq_clock(rq); - update_cfs_load(cfs_rq, 1); + struct sched_entity *se = tg->se[cpu]; + struct cfs_rq *cfs_rq = tg->cfs_rq[cpu]; - /* - * We need to update shares after updating tg->load_weight in - * order to adjust the weight of groups with long running tasks. - */ - update_cfs_shares(cfs_rq); + /* throttled entities do not contribute to load */ + if (throttled_hierarchy(cfs_rq)) + return; - raw_spin_unlock_irqrestore(&rq->lock, flags); + update_cfs_rq_blocked_load(cfs_rq, 1); - return 0; + if (se) { + update_entity_load_avg(se, 1); + /* + * We pivot on our runnable average having decayed to zero for + * list removal. This generally implies that all our children + * have also been removed (modulo rounding error or bandwidth + * control); however, such cases are rare and we can fix these + * at enqueue. + * + * TODO: fix up out-of-order children on enqueue. + */ + if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running) + list_del_leaf_cfs_rq(cfs_rq); + } else { + struct rq *rq = rq_of(cfs_rq); + update_rq_runnable_avg(rq, rq->nr_running); + } } -static void update_shares(int cpu) +static void update_blocked_averages(int cpu) { - struct cfs_rq *cfs_rq; struct rq *rq = cpu_rq(cpu); + struct cfs_rq *cfs_rq; + unsigned long flags; - rcu_read_lock(); + raw_spin_lock_irqsave(&rq->lock, flags); + update_rq_clock(rq); /* * Iterates the task_group tree in a bottom up fashion, see * list_add_leaf_cfs_rq() for details. */ for_each_leaf_cfs_rq(rq, cfs_rq) { - /* throttled entities do not contribute to load */ - if (throttled_hierarchy(cfs_rq)) - continue; - - update_shares_cpu(cfs_rq->tg, cpu); + /* + * Note: We may want to consider periodically releasing + * rq->lock about these updates so that creating many task + * groups does not result in continually extending hold time. + */ + __update_blocked_averages_cpu(cfs_rq->tg, rq->cpu); } - rcu_read_unlock(); + + raw_spin_unlock_irqrestore(&rq->lock, flags); } /* - * Compute the cpu's hierarchical load factor for each task group. + * Compute the hierarchical load factor for cfs_rq and all its ascendants. * This needs to be done in a top-down fashion because the load of a child * group is a fraction of its parents load. */ -static int tg_load_down(struct task_group *tg, void *data) +static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq) { + struct rq *rq = rq_of(cfs_rq); + struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)]; + unsigned long now = jiffies; unsigned long load; - long cpu = (long)data; - if (!tg->parent) { - load = cpu_rq(cpu)->load.weight; - } else { - load = tg->parent->cfs_rq[cpu]->h_load; - load *= tg->se[cpu]->load.weight; - load /= tg->parent->cfs_rq[cpu]->load.weight + 1; - } + if (cfs_rq->last_h_load_update == now) + return; - tg->cfs_rq[cpu]->h_load = load; + cfs_rq->h_load_next = NULL; + for_each_sched_entity(se) { + cfs_rq = cfs_rq_of(se); + cfs_rq->h_load_next = se; + if (cfs_rq->last_h_load_update == now) + break; + } - return 0; -} + if (!se) { + cfs_rq->h_load = cfs_rq->runnable_load_avg; + cfs_rq->last_h_load_update = now; + } -static void update_h_load(long cpu) -{ - walk_tg_tree(tg_load_down, tg_nop, (void *)cpu); + while ((se = cfs_rq->h_load_next) != NULL) { + load = cfs_rq->h_load; + load = div64_ul(load * se->avg.load_avg_contrib, + cfs_rq->runnable_load_avg + 1); + cfs_rq = group_cfs_rq(se); + cfs_rq->h_load = load; + cfs_rq->last_h_load_update = now; + } } -static unsigned long -load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, - unsigned long max_load_move, - struct sched_domain *sd, enum cpu_idle_type idle, - int *lb_flags) +static unsigned long task_h_load(struct task_struct *p) { - long rem_load_move = max_load_move; - struct cfs_rq *busiest_cfs_rq; - - rcu_read_lock(); - update_h_load(cpu_of(busiest)); - - for_each_leaf_cfs_rq(busiest, busiest_cfs_rq) { - unsigned long busiest_h_load = busiest_cfs_rq->h_load; - unsigned long busiest_weight = busiest_cfs_rq->load.weight; - u64 rem_load, moved_load; - - if (*lb_flags & (LBF_NEED_BREAK|LBF_ABORT)) - break; - - /* - * empty group or part of a throttled hierarchy - */ - if (!busiest_cfs_rq->task_weight || - throttled_lb_pair(busiest_cfs_rq->tg, cpu_of(busiest), this_cpu)) - continue; - - rem_load = (u64)rem_load_move * busiest_weight; - rem_load = div_u64(rem_load, busiest_h_load + 1); - - moved_load = balance_tasks(this_rq, this_cpu, busiest, - rem_load, sd, idle, lb_flags, - busiest_cfs_rq); - - if (!moved_load) - continue; - - moved_load *= busiest_h_load; - moved_load = div_u64(moved_load, busiest_weight + 1); + struct cfs_rq *cfs_rq = task_cfs_rq(p); - rem_load_move -= moved_load; - if (rem_load_move < 0) - break; - } - rcu_read_unlock(); - - return max_load_move - rem_load_move; + update_cfs_rq_h_load(cfs_rq); + return div64_ul(p->se.avg.load_avg_contrib * cfs_rq->h_load, + cfs_rq->runnable_load_avg + 1); } #else -static inline void update_shares(int cpu) +static inline void update_blocked_averages(int cpu) { } -static unsigned long -load_balance_fair(struct rq *this_rq, int this_cpu, struct rq *busiest, - unsigned long max_load_move, - struct sched_domain *sd, enum cpu_idle_type idle, - int *lb_flags) +static unsigned long task_h_load(struct task_struct *p) { - return balance_tasks(this_rq, this_cpu, busiest, - max_load_move, sd, idle, lb_flags, - &busiest->cfs); + return p->se.avg.load_avg_contrib; } #endif -/* - * move_tasks tries to move up to max_load_move weighted load from busiest to - * this_rq, as part of a balancing operation within domain "sd". - * Returns 1 if successful and 0 otherwise. - * - * Called with both runqueues locked. - */ -static int move_tasks(struct rq *this_rq, int this_cpu, struct rq *busiest, - unsigned long max_load_move, - struct sched_domain *sd, enum cpu_idle_type idle, - int *lb_flags) -{ - unsigned long total_load_moved = 0, load_moved; - - do { - load_moved = load_balance_fair(this_rq, this_cpu, busiest, - max_load_move - total_load_moved, - sd, idle, lb_flags); - - total_load_moved += load_moved; - - if (*lb_flags & (LBF_NEED_BREAK|LBF_ABORT)) - break; - -#ifdef CONFIG_PREEMPT - /* - * NEWIDLE balancing is a source of latency, so preemptible - * kernels will stop after the first task is pulled to minimize - * the critical section. - */ - if (idle == CPU_NEWLY_IDLE && this_rq->nr_running) { - *lb_flags |= LBF_ABORT; - break; - } -#endif - } while (load_moved && max_load_move > total_load_moved); - - return total_load_moved > 0; -} - /********** Helpers for find_busiest_group ************************/ /* - * sd_lb_stats - Structure to store the statistics of a sched_domain - * during load balancing. - */ -struct sd_lb_stats { - struct sched_group *busiest; /* Busiest group in this sd */ - struct sched_group *this; /* Local group in this sd */ - unsigned long total_load; /* Total load of all groups in sd */ - unsigned long total_pwr; /* Total power of all groups in sd */ - unsigned long avg_load; /* Average load across all groups in sd */ - - /** Statistics of this group */ - unsigned long this_load; - unsigned long this_load_per_task; - unsigned long this_nr_running; - unsigned long this_has_capacity; - unsigned int this_idle_cpus; - - /* Statistics of the busiest group */ - unsigned int busiest_idle_cpus; - unsigned long max_load; - unsigned long busiest_load_per_task; - unsigned long busiest_nr_running; - unsigned long busiest_group_capacity; - unsigned long busiest_has_capacity; - unsigned int busiest_group_weight; - - int group_imb; /* Is there imbalance in this sd */ -#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) - int power_savings_balance; /* Is powersave balance needed for this sd */ - struct sched_group *group_min; /* Least loaded group in sd */ - struct sched_group *group_leader; /* Group which relieves group_min */ - unsigned long min_load_per_task; /* load_per_task in group_min */ - unsigned long leader_nr_running; /* Nr running of group_leader */ - unsigned long min_nr_running; /* Nr running of group_min */ -#endif -}; - -/* * sg_lb_stats - stats of a sched_group required for load_balancing */ struct sg_lb_stats { unsigned long avg_load; /*Avg load across the CPUs of the group */ unsigned long group_load; /* Total load over the CPUs of the group */ - unsigned long sum_nr_running; /* Nr tasks running in the group */ unsigned long sum_weighted_load; /* Weighted load of group's tasks */ + unsigned long load_per_task; unsigned long group_capacity; - unsigned long idle_cpus; - unsigned long group_weight; + unsigned int sum_nr_running; /* Nr tasks running in the group */ + unsigned int group_capacity_factor; + unsigned int idle_cpus; + unsigned int group_weight; int group_imb; /* Is there an imbalance in the group ? */ - int group_has_capacity; /* Is there extra capacity in the group? */ + int group_has_free_capacity; +#ifdef CONFIG_NUMA_BALANCING + unsigned int nr_numa_running; + unsigned int nr_preferred_running; +#endif }; +/* + * sd_lb_stats - Structure to store the statistics of a sched_domain + * during load balancing. + */ +struct sd_lb_stats { + struct sched_group *busiest; /* Busiest group in this sd */ + struct sched_group *local; /* Local group in this sd */ + unsigned long total_load; /* Total load of all groups in sd */ + unsigned long total_capacity; /* Total capacity of all groups in sd */ + unsigned long avg_load; /* Average load across all groups in sd */ + + struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */ + struct sg_lb_stats local_stat; /* Statistics of the local group */ +}; + +static inline void init_sd_lb_stats(struct sd_lb_stats *sds) +{ + /* + * Skimp on the clearing to avoid duplicate work. We can avoid clearing + * local_stat because update_sg_lb_stats() does a full clear/assignment. + * We must however clear busiest_stat::avg_load because + * update_sd_pick_busiest() reads this before assignment. + */ + *sds = (struct sd_lb_stats){ + .busiest = NULL, + .local = NULL, + .total_load = 0UL, + .total_capacity = 0UL, + .busiest_stat = { + .avg_load = 0UL, + }, + }; +} + /** * get_sd_load_idx - Obtain the load index for a given sched domain. * @sd: The sched_domain whose load_idx is to be obtained. - * @idle: The Idle status of the CPU for whose sd load_icx is obtained. + * @idle: The idle status of the CPU for whose sd load_idx is obtained. + * + * Return: The load index. */ static inline int get_sd_load_idx(struct sched_domain *sd, enum cpu_idle_type idle) @@ -3548,159 +5608,17 @@ static inline int get_sd_load_idx(struct sched_domain *sd, return load_idx; } - -#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) -/** - * init_sd_power_savings_stats - Initialize power savings statistics for - * the given sched_domain, during load balancing. - * - * @sd: Sched domain whose power-savings statistics are to be initialized. - * @sds: Variable containing the statistics for sd. - * @idle: Idle status of the CPU at which we're performing load-balancing. - */ -static inline void init_sd_power_savings_stats(struct sched_domain *sd, - struct sd_lb_stats *sds, enum cpu_idle_type idle) +static unsigned long default_scale_capacity(struct sched_domain *sd, int cpu) { - /* - * Busy processors will not participate in power savings - * balance. - */ - if (idle == CPU_NOT_IDLE || !(sd->flags & SD_POWERSAVINGS_BALANCE)) - sds->power_savings_balance = 0; - else { - sds->power_savings_balance = 1; - sds->min_nr_running = ULONG_MAX; - sds->leader_nr_running = 0; - } + return SCHED_CAPACITY_SCALE; } -/** - * update_sd_power_savings_stats - Update the power saving stats for a - * sched_domain while performing load balancing. - * - * @group: sched_group belonging to the sched_domain under consideration. - * @sds: Variable containing the statistics of the sched_domain - * @local_group: Does group contain the CPU for which we're performing - * load balancing ? - * @sgs: Variable containing the statistics of the group. - */ -static inline void update_sd_power_savings_stats(struct sched_group *group, - struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs) +unsigned long __weak arch_scale_freq_capacity(struct sched_domain *sd, int cpu) { - - if (!sds->power_savings_balance) - return; - - /* - * If the local group is idle or completely loaded - * no need to do power savings balance at this domain - */ - if (local_group && (sds->this_nr_running >= sgs->group_capacity || - !sds->this_nr_running)) - sds->power_savings_balance = 0; - - /* - * If a group is already running at full capacity or idle, - * don't include that group in power savings calculations - */ - if (!sds->power_savings_balance || - sgs->sum_nr_running >= sgs->group_capacity || - !sgs->sum_nr_running) - return; - - /* - * Calculate the group which has the least non-idle load. - * This is the group from where we need to pick up the load - * for saving power - */ - if ((sgs->sum_nr_running < sds->min_nr_running) || - (sgs->sum_nr_running == sds->min_nr_running && - group_first_cpu(group) > group_first_cpu(sds->group_min))) { - sds->group_min = group; - sds->min_nr_running = sgs->sum_nr_running; - sds->min_load_per_task = sgs->sum_weighted_load / - sgs->sum_nr_running; - } - - /* - * Calculate the group which is almost near its - * capacity but still has some space to pick up some load - * from other group and save more power - */ - if (sgs->sum_nr_running + 1 > sgs->group_capacity) - return; - - if (sgs->sum_nr_running > sds->leader_nr_running || - (sgs->sum_nr_running == sds->leader_nr_running && - group_first_cpu(group) < group_first_cpu(sds->group_leader))) { - sds->group_leader = group; - sds->leader_nr_running = sgs->sum_nr_running; - } + return default_scale_capacity(sd, cpu); } -/** - * check_power_save_busiest_group - see if there is potential for some power-savings balance - * @sds: Variable containing the statistics of the sched_domain - * under consideration. - * @this_cpu: Cpu at which we're currently performing load-balancing. - * @imbalance: Variable to store the imbalance. - * - * Description: - * Check if we have potential to perform some power-savings balance. - * If yes, set the busiest group to be the least loaded group in the - * sched_domain, so that it's CPUs can be put to idle. - * - * Returns 1 if there is potential to perform power-savings balance. - * Else returns 0. - */ -static inline int check_power_save_busiest_group(struct sd_lb_stats *sds, - int this_cpu, unsigned long *imbalance) -{ - if (!sds->power_savings_balance) - return 0; - - if (sds->this != sds->group_leader || - sds->group_leader == sds->group_min) - return 0; - - *imbalance = sds->min_load_per_task; - sds->busiest = sds->group_min; - - return 1; - -} -#else /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */ -static inline void init_sd_power_savings_stats(struct sched_domain *sd, - struct sd_lb_stats *sds, enum cpu_idle_type idle) -{ - return; -} - -static inline void update_sd_power_savings_stats(struct sched_group *group, - struct sd_lb_stats *sds, int local_group, struct sg_lb_stats *sgs) -{ - return; -} - -static inline int check_power_save_busiest_group(struct sd_lb_stats *sds, - int this_cpu, unsigned long *imbalance) -{ - return 0; -} -#endif /* CONFIG_SCHED_MC || CONFIG_SCHED_SMT */ - - -unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu) -{ - return SCHED_POWER_SCALE; -} - -unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu) -{ - return default_scale_freq_power(sd, cpu); -} - -unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu) +static unsigned long default_scale_smt_capacity(struct sched_domain *sd, int cpu) { unsigned long weight = sd->span_weight; unsigned long smt_gain = sd->smt_gain; @@ -3710,87 +5628,146 @@ unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu) return smt_gain; } -unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu) +unsigned long __weak arch_scale_smt_capacity(struct sched_domain *sd, int cpu) { - return default_scale_smt_power(sd, cpu); + return default_scale_smt_capacity(sd, cpu); } -unsigned long scale_rt_power(int cpu) +static unsigned long scale_rt_capacity(int cpu) { struct rq *rq = cpu_rq(cpu); - u64 total, available; + u64 total, available, age_stamp, avg; + s64 delta; - total = sched_avg_period() + (rq->clock - rq->age_stamp); + /* + * Since we're reading these variables without serialization make sure + * we read them once before doing sanity checks on them. + */ + age_stamp = ACCESS_ONCE(rq->age_stamp); + avg = ACCESS_ONCE(rq->rt_avg); - if (unlikely(total < rq->rt_avg)) { - /* Ensures that power won't end up being negative */ + delta = rq_clock(rq) - age_stamp; + if (unlikely(delta < 0)) + delta = 0; + + total = sched_avg_period() + delta; + + if (unlikely(total < avg)) { + /* Ensures that capacity won't end up being negative */ available = 0; } else { - available = total - rq->rt_avg; + available = total - avg; } - if (unlikely((s64)total < SCHED_POWER_SCALE)) - total = SCHED_POWER_SCALE; + if (unlikely((s64)total < SCHED_CAPACITY_SCALE)) + total = SCHED_CAPACITY_SCALE; - total >>= SCHED_POWER_SHIFT; + total >>= SCHED_CAPACITY_SHIFT; return div_u64(available, total); } -static void update_cpu_power(struct sched_domain *sd, int cpu) +static void update_cpu_capacity(struct sched_domain *sd, int cpu) { unsigned long weight = sd->span_weight; - unsigned long power = SCHED_POWER_SCALE; + unsigned long capacity = SCHED_CAPACITY_SCALE; struct sched_group *sdg = sd->groups; - if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) { - if (sched_feat(ARCH_POWER)) - power *= arch_scale_smt_power(sd, cpu); + if ((sd->flags & SD_SHARE_CPUCAPACITY) && weight > 1) { + if (sched_feat(ARCH_CAPACITY)) + capacity *= arch_scale_smt_capacity(sd, cpu); else - power *= default_scale_smt_power(sd, cpu); + capacity *= default_scale_smt_capacity(sd, cpu); - power >>= SCHED_POWER_SHIFT; + capacity >>= SCHED_CAPACITY_SHIFT; } - sdg->sgp->power_orig = power; + sdg->sgc->capacity_orig = capacity; - if (sched_feat(ARCH_POWER)) - power *= arch_scale_freq_power(sd, cpu); + if (sched_feat(ARCH_CAPACITY)) + capacity *= arch_scale_freq_capacity(sd, cpu); else - power *= default_scale_freq_power(sd, cpu); + capacity *= default_scale_capacity(sd, cpu); - power >>= SCHED_POWER_SHIFT; + capacity >>= SCHED_CAPACITY_SHIFT; - power *= scale_rt_power(cpu); - power >>= SCHED_POWER_SHIFT; + capacity *= scale_rt_capacity(cpu); + capacity >>= SCHED_CAPACITY_SHIFT; - if (!power) - power = 1; + if (!capacity) + capacity = 1; - cpu_rq(cpu)->cpu_power = power; - sdg->sgp->power = power; + cpu_rq(cpu)->cpu_capacity = capacity; + sdg->sgc->capacity = capacity; } -void update_group_power(struct sched_domain *sd, int cpu) +void update_group_capacity(struct sched_domain *sd, int cpu) { struct sched_domain *child = sd->child; struct sched_group *group, *sdg = sd->groups; - unsigned long power; + unsigned long capacity, capacity_orig; + unsigned long interval; + + interval = msecs_to_jiffies(sd->balance_interval); + interval = clamp(interval, 1UL, max_load_balance_interval); + sdg->sgc->next_update = jiffies + interval; if (!child) { - update_cpu_power(sd, cpu); + update_cpu_capacity(sd, cpu); return; } - power = 0; + capacity_orig = capacity = 0; - group = child->groups; - do { - power += group->sgp->power; - group = group->next; - } while (group != child->groups); + if (child->flags & SD_OVERLAP) { + /* + * SD_OVERLAP domains cannot assume that child groups + * span the current group. + */ + + for_each_cpu(cpu, sched_group_cpus(sdg)) { + struct sched_group_capacity *sgc; + struct rq *rq = cpu_rq(cpu); + + /* + * build_sched_domains() -> init_sched_groups_capacity() + * gets here before we've attached the domains to the + * runqueues. + * + * Use capacity_of(), which is set irrespective of domains + * in update_cpu_capacity(). + * + * This avoids capacity/capacity_orig from being 0 and + * causing divide-by-zero issues on boot. + * + * Runtime updates will correct capacity_orig. + */ + if (unlikely(!rq->sd)) { + capacity_orig += capacity_of(cpu); + capacity += capacity_of(cpu); + continue; + } + + sgc = rq->sd->groups->sgc; + capacity_orig += sgc->capacity_orig; + capacity += sgc->capacity; + } + } else { + /* + * !SD_OVERLAP domains can assume that child groups + * span the current group. + */ - sdg->sgp->power = power; + group = child->groups; + do { + capacity_orig += group->sgc->capacity_orig; + capacity += group->sgc->capacity; + group = group->next; + } while (group != child->groups); + } + + sdg->sgc->capacity_orig = capacity_orig; + sdg->sgc->capacity = capacity; } /* @@ -3804,142 +5781,157 @@ static inline int fix_small_capacity(struct sched_domain *sd, struct sched_group *group) { /* - * Only siblings can have significantly less than SCHED_POWER_SCALE + * Only siblings can have significantly less than SCHED_CAPACITY_SCALE */ - if (!(sd->flags & SD_SHARE_CPUPOWER)) + if (!(sd->flags & SD_SHARE_CPUCAPACITY)) return 0; /* - * If ~90% of the cpu_power is still there, we're good. + * If ~90% of the cpu_capacity is still there, we're good. */ - if (group->sgp->power * 32 > group->sgp->power_orig * 29) + if (group->sgc->capacity * 32 > group->sgc->capacity_orig * 29) return 1; return 0; } +/* + * Group imbalance indicates (and tries to solve) the problem where balancing + * groups is inadequate due to tsk_cpus_allowed() constraints. + * + * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a + * cpumask covering 1 cpu of the first group and 3 cpus of the second group. + * Something like: + * + * { 0 1 2 3 } { 4 5 6 7 } + * * * * * + * + * If we were to balance group-wise we'd place two tasks in the first group and + * two tasks in the second group. Clearly this is undesired as it will overload + * cpu 3 and leave one of the cpus in the second group unused. + * + * The current solution to this issue is detecting the skew in the first group + * by noticing the lower domain failed to reach balance and had difficulty + * moving tasks due to affinity constraints. + * + * When this is so detected; this group becomes a candidate for busiest; see + * update_sd_pick_busiest(). And calculate_imbalance() and + * find_busiest_group() avoid some of the usual balance conditions to allow it + * to create an effective group imbalance. + * + * This is a somewhat tricky proposition since the next run might not find the + * group imbalance and decide the groups need to be balanced again. A most + * subtle and fragile situation. + */ + +static inline int sg_imbalanced(struct sched_group *group) +{ + return group->sgc->imbalance; +} + +/* + * Compute the group capacity factor. + * + * Avoid the issue where N*frac(smt_capacity) >= 1 creates 'phantom' cores by + * first dividing out the smt factor and computing the actual number of cores + * and limit unit capacity with that. + */ +static inline int sg_capacity_factor(struct lb_env *env, struct sched_group *group) +{ + unsigned int capacity_factor, smt, cpus; + unsigned int capacity, capacity_orig; + + capacity = group->sgc->capacity; + capacity_orig = group->sgc->capacity_orig; + cpus = group->group_weight; + + /* smt := ceil(cpus / capacity), assumes: 1 < smt_capacity < 2 */ + smt = DIV_ROUND_UP(SCHED_CAPACITY_SCALE * cpus, capacity_orig); + capacity_factor = cpus / smt; /* cores */ + + capacity_factor = min_t(unsigned, + capacity_factor, DIV_ROUND_CLOSEST(capacity, SCHED_CAPACITY_SCALE)); + if (!capacity_factor) + capacity_factor = fix_small_capacity(env->sd, group); + + return capacity_factor; +} + /** * update_sg_lb_stats - Update sched_group's statistics for load balancing. - * @sd: The sched_domain whose statistics are to be updated. + * @env: The load balancing environment. * @group: sched_group whose statistics are to be updated. - * @this_cpu: Cpu for which load balance is currently performed. - * @idle: Idle status of this_cpu * @load_idx: Load index of sched_domain of this_cpu for load calc. * @local_group: Does group contain this_cpu. - * @cpus: Set of cpus considered for load balancing. - * @balance: Should we balance. * @sgs: variable to hold the statistics for this group. */ -static inline void update_sg_lb_stats(struct sched_domain *sd, - struct sched_group *group, int this_cpu, - enum cpu_idle_type idle, int load_idx, - int local_group, const struct cpumask *cpus, - int *balance, struct sg_lb_stats *sgs) +static inline void update_sg_lb_stats(struct lb_env *env, + struct sched_group *group, int load_idx, + int local_group, struct sg_lb_stats *sgs) { - unsigned long load, max_cpu_load, min_cpu_load, max_nr_running; + unsigned long load; int i; - unsigned int balance_cpu = -1, first_idle_cpu = 0; - unsigned long avg_load_per_task = 0; - if (local_group) - balance_cpu = group_first_cpu(group); + memset(sgs, 0, sizeof(*sgs)); - /* Tally up the load of all CPUs in the group */ - max_cpu_load = 0; - min_cpu_load = ~0UL; - max_nr_running = 0; - - for_each_cpu_and(i, sched_group_cpus(group), cpus) { + for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { struct rq *rq = cpu_rq(i); /* Bias balancing toward cpus of our domain */ - if (local_group) { - if (idle_cpu(i) && !first_idle_cpu) { - first_idle_cpu = 1; - balance_cpu = i; - } - + if (local_group) load = target_load(i, load_idx); - } else { + else load = source_load(i, load_idx); - if (load > max_cpu_load) { - max_cpu_load = load; - max_nr_running = rq->nr_running; - } - if (min_cpu_load > load) - min_cpu_load = load; - } sgs->group_load += load; sgs->sum_nr_running += rq->nr_running; +#ifdef CONFIG_NUMA_BALANCING + sgs->nr_numa_running += rq->nr_numa_running; + sgs->nr_preferred_running += rq->nr_preferred_running; +#endif sgs->sum_weighted_load += weighted_cpuload(i); if (idle_cpu(i)) sgs->idle_cpus++; } - /* - * First idle cpu or the first cpu(busiest) in this sched group - * is eligible for doing load balancing at this and above - * domains. In the newly idle case, we will allow all the cpu's - * to do the newly idle load balance. - */ - if (idle != CPU_NEWLY_IDLE && local_group) { - if (balance_cpu != this_cpu) { - *balance = 0; - return; - } - update_group_power(sd, this_cpu); - } - - /* Adjust by relative CPU power of the group */ - sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power; + /* Adjust by relative CPU capacity of the group */ + sgs->group_capacity = group->sgc->capacity; + sgs->avg_load = (sgs->group_load*SCHED_CAPACITY_SCALE) / sgs->group_capacity; - /* - * Consider the group unbalanced when the imbalance is larger - * than the average weight of a task. - * - * APZ: with cgroup the avg task weight can vary wildly and - * might not be a suitable number - should we keep a - * normalized nr_running number somewhere that negates - * the hierarchy? - */ if (sgs->sum_nr_running) - avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; + sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; - if ((max_cpu_load - min_cpu_load) >= avg_load_per_task && max_nr_running > 1) - sgs->group_imb = 1; - - sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power, - SCHED_POWER_SCALE); - if (!sgs->group_capacity) - sgs->group_capacity = fix_small_capacity(sd, group); sgs->group_weight = group->group_weight; - if (sgs->group_capacity > sgs->sum_nr_running) - sgs->group_has_capacity = 1; + sgs->group_imb = sg_imbalanced(group); + sgs->group_capacity_factor = sg_capacity_factor(env, group); + + if (sgs->group_capacity_factor > sgs->sum_nr_running) + sgs->group_has_free_capacity = 1; } /** * update_sd_pick_busiest - return 1 on busiest group - * @sd: sched_domain whose statistics are to be checked + * @env: The load balancing environment. * @sds: sched_domain statistics * @sg: sched_group candidate to be checked for being the busiest * @sgs: sched_group statistics - * @this_cpu: the current cpu * * Determine if @sg is a busier group than the previously selected * busiest group. + * + * Return: %true if @sg is a busier group than the previously selected + * busiest group. %false otherwise. */ -static bool update_sd_pick_busiest(struct sched_domain *sd, +static bool update_sd_pick_busiest(struct lb_env *env, struct sd_lb_stats *sds, struct sched_group *sg, - struct sg_lb_stats *sgs, - int this_cpu) + struct sg_lb_stats *sgs) { - if (sgs->avg_load <= sds->max_load) + if (sgs->avg_load <= sds->busiest_stat.avg_load) return false; - if (sgs->sum_nr_running > sgs->group_capacity) + if (sgs->sum_nr_running > sgs->group_capacity_factor) return true; if (sgs->group_imb) @@ -3950,8 +5942,8 @@ static bool update_sd_pick_busiest(struct sched_domain *sd, * numbered CPUs in the group, therefore mark all groups * higher than ourself as busy. */ - if ((sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running && - this_cpu < group_first_cpu(sg)) { + if ((env->sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running && + env->dst_cpu < group_first_cpu(sg)) { if (!sds->busiest) return true; @@ -3962,79 +5954,101 @@ static bool update_sd_pick_busiest(struct sched_domain *sd, return false; } +#ifdef CONFIG_NUMA_BALANCING +static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) +{ + if (sgs->sum_nr_running > sgs->nr_numa_running) + return regular; + if (sgs->sum_nr_running > sgs->nr_preferred_running) + return remote; + return all; +} + +static inline enum fbq_type fbq_classify_rq(struct rq *rq) +{ + if (rq->nr_running > rq->nr_numa_running) + return regular; + if (rq->nr_running > rq->nr_preferred_running) + return remote; + return all; +} +#else +static inline enum fbq_type fbq_classify_group(struct sg_lb_stats *sgs) +{ + return all; +} + +static inline enum fbq_type fbq_classify_rq(struct rq *rq) +{ + return regular; +} +#endif /* CONFIG_NUMA_BALANCING */ + /** * update_sd_lb_stats - Update sched_domain's statistics for load balancing. - * @sd: sched_domain whose statistics are to be updated. - * @this_cpu: Cpu for which load balance is currently performed. - * @idle: Idle status of this_cpu - * @cpus: Set of cpus considered for load balancing. - * @balance: Should we balance. + * @env: The load balancing environment. * @sds: variable to hold the statistics for this sched_domain. */ -static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu, - enum cpu_idle_type idle, const struct cpumask *cpus, - int *balance, struct sd_lb_stats *sds) +static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sds) { - struct sched_domain *child = sd->child; - struct sched_group *sg = sd->groups; - struct sg_lb_stats sgs; + struct sched_domain *child = env->sd->child; + struct sched_group *sg = env->sd->groups; + struct sg_lb_stats tmp_sgs; int load_idx, prefer_sibling = 0; if (child && child->flags & SD_PREFER_SIBLING) prefer_sibling = 1; - init_sd_power_savings_stats(sd, sds, idle); - load_idx = get_sd_load_idx(sd, idle); + load_idx = get_sd_load_idx(env->sd, env->idle); do { + struct sg_lb_stats *sgs = &tmp_sgs; int local_group; - local_group = cpumask_test_cpu(this_cpu, sched_group_cpus(sg)); - memset(&sgs, 0, sizeof(sgs)); - update_sg_lb_stats(sd, sg, this_cpu, idle, load_idx, - local_group, cpus, balance, &sgs); + local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg)); + if (local_group) { + sds->local = sg; + sgs = &sds->local_stat; - if (local_group && !(*balance)) - return; + if (env->idle != CPU_NEWLY_IDLE || + time_after_eq(jiffies, sg->sgc->next_update)) + update_group_capacity(env->sd, env->dst_cpu); + } + + update_sg_lb_stats(env, sg, load_idx, local_group, sgs); - sds->total_load += sgs.group_load; - sds->total_pwr += sg->sgp->power; + if (local_group) + goto next_group; /* * In case the child domain prefers tasks go to siblings - * first, lower the sg capacity to one so that we'll try + * first, lower the sg capacity factor to one so that we'll try * and move all the excess tasks away. We lower the capacity * of a group only if the local group has the capacity to fit - * these excess tasks, i.e. nr_running < group_capacity. The + * these excess tasks, i.e. nr_running < group_capacity_factor. The * extra check prevents the case where you always pull from the * heaviest group when it is already under-utilized (possible * with a large weight task outweighs the tasks on the system). */ - if (prefer_sibling && !local_group && sds->this_has_capacity) - sgs.group_capacity = min(sgs.group_capacity, 1UL); + if (prefer_sibling && sds->local && + sds->local_stat.group_has_free_capacity) + sgs->group_capacity_factor = min(sgs->group_capacity_factor, 1U); - if (local_group) { - sds->this_load = sgs.avg_load; - sds->this = sg; - sds->this_nr_running = sgs.sum_nr_running; - sds->this_load_per_task = sgs.sum_weighted_load; - sds->this_has_capacity = sgs.group_has_capacity; - sds->this_idle_cpus = sgs.idle_cpus; - } else if (update_sd_pick_busiest(sd, sds, sg, &sgs, this_cpu)) { - sds->max_load = sgs.avg_load; + if (update_sd_pick_busiest(env, sds, sg, sgs)) { sds->busiest = sg; - sds->busiest_nr_running = sgs.sum_nr_running; - sds->busiest_idle_cpus = sgs.idle_cpus; - sds->busiest_group_capacity = sgs.group_capacity; - sds->busiest_load_per_task = sgs.sum_weighted_load; - sds->busiest_has_capacity = sgs.group_has_capacity; - sds->busiest_group_weight = sgs.group_weight; - sds->group_imb = sgs.group_imb; + sds->busiest_stat = *sgs; } - update_sd_power_savings_stats(sg, sds, local_group, &sgs); +next_group: + /* Now, start updating sd_lb_stats */ + sds->total_load += sgs->group_load; + sds->total_capacity += sgs->group_capacity; + sg = sg->next; - } while (sg != sd->groups); + } while (sg != env->sd->groups); + + if (env->sd->flags & SD_NUMA) + env->fbq_type = fbq_classify_group(&sds->busiest_stat); } /** @@ -4054,32 +6068,30 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu, * assuming lower CPU number will be equivalent to lower a SMT thread * number. * - * Returns 1 when packing is required and a task should be moved to + * Return: 1 when packing is required and a task should be moved to * this CPU. The amount of the imbalance is returned in *imbalance. * - * @sd: The sched_domain whose packing is to be checked. + * @env: The load balancing environment. * @sds: Statistics of the sched_domain which is to be packed - * @this_cpu: The cpu at whose sched_domain we're performing load-balance. - * @imbalance: returns amount of imbalanced due to packing. */ -static int check_asym_packing(struct sched_domain *sd, - struct sd_lb_stats *sds, - int this_cpu, unsigned long *imbalance) +static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds) { int busiest_cpu; - if (!(sd->flags & SD_ASYM_PACKING)) + if (!(env->sd->flags & SD_ASYM_PACKING)) return 0; if (!sds->busiest) return 0; busiest_cpu = group_first_cpu(sds->busiest); - if (this_cpu > busiest_cpu) + if (env->dst_cpu > busiest_cpu) return 0; - *imbalance = DIV_ROUND_CLOSEST(sds->max_load * sds->busiest->sgp->power, - SCHED_POWER_SCALE); + env->imbalance = DIV_ROUND_CLOSEST( + sds->busiest_stat.avg_load * sds->busiest_stat.group_capacity, + SCHED_CAPACITY_SCALE); + return 1; } @@ -4087,110 +6099,117 @@ static int check_asym_packing(struct sched_domain *sd, * fix_small_imbalance - Calculate the minor imbalance that exists * amongst the groups of a sched_domain, during * load balancing. + * @env: The load balancing environment. * @sds: Statistics of the sched_domain whose imbalance is to be calculated. - * @this_cpu: The cpu at whose sched_domain we're performing load-balance. - * @imbalance: Variable to store the imbalance. */ -static inline void fix_small_imbalance(struct sd_lb_stats *sds, - int this_cpu, unsigned long *imbalance) +static inline +void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) { - unsigned long tmp, pwr_now = 0, pwr_move = 0; + unsigned long tmp, capa_now = 0, capa_move = 0; unsigned int imbn = 2; unsigned long scaled_busy_load_per_task; + struct sg_lb_stats *local, *busiest; - if (sds->this_nr_running) { - sds->this_load_per_task /= sds->this_nr_running; - if (sds->busiest_load_per_task > - sds->this_load_per_task) - imbn = 1; - } else - sds->this_load_per_task = - cpu_avg_load_per_task(this_cpu); + local = &sds->local_stat; + busiest = &sds->busiest_stat; + + if (!local->sum_nr_running) + local->load_per_task = cpu_avg_load_per_task(env->dst_cpu); + else if (busiest->load_per_task > local->load_per_task) + imbn = 1; - scaled_busy_load_per_task = sds->busiest_load_per_task - * SCHED_POWER_SCALE; - scaled_busy_load_per_task /= sds->busiest->sgp->power; + scaled_busy_load_per_task = + (busiest->load_per_task * SCHED_CAPACITY_SCALE) / + busiest->group_capacity; - if (sds->max_load - sds->this_load + scaled_busy_load_per_task >= - (scaled_busy_load_per_task * imbn)) { - *imbalance = sds->busiest_load_per_task; + if (busiest->avg_load + scaled_busy_load_per_task >= + local->avg_load + (scaled_busy_load_per_task * imbn)) { + env->imbalance = busiest->load_per_task; return; } /* * OK, we don't have enough imbalance to justify moving tasks, - * however we may be able to increase total CPU power used by + * however we may be able to increase total CPU capacity used by * moving them. */ - pwr_now += sds->busiest->sgp->power * - min(sds->busiest_load_per_task, sds->max_load); - pwr_now += sds->this->sgp->power * - min(sds->this_load_per_task, sds->this_load); - pwr_now /= SCHED_POWER_SCALE; + capa_now += busiest->group_capacity * + min(busiest->load_per_task, busiest->avg_load); + capa_now += local->group_capacity * + min(local->load_per_task, local->avg_load); + capa_now /= SCHED_CAPACITY_SCALE; /* Amount of load we'd subtract */ - tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) / - sds->busiest->sgp->power; - if (sds->max_load > tmp) - pwr_move += sds->busiest->sgp->power * - min(sds->busiest_load_per_task, sds->max_load - tmp); + if (busiest->avg_load > scaled_busy_load_per_task) { + capa_move += busiest->group_capacity * + min(busiest->load_per_task, + busiest->avg_load - scaled_busy_load_per_task); + } /* Amount of load we'd add */ - if (sds->max_load * sds->busiest->sgp->power < - sds->busiest_load_per_task * SCHED_POWER_SCALE) - tmp = (sds->max_load * sds->busiest->sgp->power) / - sds->this->sgp->power; - else - tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) / - sds->this->sgp->power; - pwr_move += sds->this->sgp->power * - min(sds->this_load_per_task, sds->this_load + tmp); - pwr_move /= SCHED_POWER_SCALE; + if (busiest->avg_load * busiest->group_capacity < + busiest->load_per_task * SCHED_CAPACITY_SCALE) { + tmp = (busiest->avg_load * busiest->group_capacity) / + local->group_capacity; + } else { + tmp = (busiest->load_per_task * SCHED_CAPACITY_SCALE) / + local->group_capacity; + } + capa_move += local->group_capacity * + min(local->load_per_task, local->avg_load + tmp); + capa_move /= SCHED_CAPACITY_SCALE; /* Move if we gain throughput */ - if (pwr_move > pwr_now) - *imbalance = sds->busiest_load_per_task; + if (capa_move > capa_now) + env->imbalance = busiest->load_per_task; } /** * calculate_imbalance - Calculate the amount of imbalance present within the * groups of a given sched_domain during load balance. + * @env: load balance environment * @sds: statistics of the sched_domain whose imbalance is to be calculated. - * @this_cpu: Cpu for which currently load balance is being performed. - * @imbalance: The variable to store the imbalance. */ -static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu, - unsigned long *imbalance) +static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds) { unsigned long max_pull, load_above_capacity = ~0UL; + struct sg_lb_stats *local, *busiest; - sds->busiest_load_per_task /= sds->busiest_nr_running; - if (sds->group_imb) { - sds->busiest_load_per_task = - min(sds->busiest_load_per_task, sds->avg_load); + local = &sds->local_stat; + busiest = &sds->busiest_stat; + + if (busiest->group_imb) { + /* + * In the group_imb case we cannot rely on group-wide averages + * to ensure cpu-load equilibrium, look at wider averages. XXX + */ + busiest->load_per_task = + min(busiest->load_per_task, sds->avg_load); } /* * In the presence of smp nice balancing, certain scenarios can have * max load less than avg load(as we skip the groups at or below - * its cpu_power, while calculating max_load..) + * its cpu_capacity, while calculating max_load..) */ - if (sds->max_load < sds->avg_load) { - *imbalance = 0; - return fix_small_imbalance(sds, this_cpu, imbalance); + if (busiest->avg_load <= sds->avg_load || + local->avg_load >= sds->avg_load) { + env->imbalance = 0; + return fix_small_imbalance(env, sds); } - if (!sds->group_imb) { + if (!busiest->group_imb) { /* * Don't want to pull so many tasks that a group would go idle. + * Except of course for the group_imb case, since then we might + * have to drop below capacity to reach cpu-load equilibrium. */ - load_above_capacity = (sds->busiest_nr_running - - sds->busiest_group_capacity); + load_above_capacity = + (busiest->sum_nr_running - busiest->group_capacity_factor); - load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE); - - load_above_capacity /= sds->busiest->sgp->power; + load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_CAPACITY_SCALE); + load_above_capacity /= busiest->group_capacity; } /* @@ -4200,15 +6219,14 @@ static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu, * we also don't want to reduce the group load below the group capacity * (so that we can implement power-savings policies etc). Thus we look * for the minimum possible imbalance. - * Be careful of negative numbers as they'll appear as very large values - * with unsigned longs. */ - max_pull = min(sds->max_load - sds->avg_load, load_above_capacity); + max_pull = min(busiest->avg_load - sds->avg_load, load_above_capacity); /* How much load to actually move to equalise the imbalance */ - *imbalance = min(max_pull * sds->busiest->sgp->power, - (sds->avg_load - sds->this_load) * sds->this->sgp->power) - / SCHED_POWER_SCALE; + env->imbalance = min( + max_pull * busiest->group_capacity, + (sds->avg_load - local->avg_load) * local->group_capacity + ) / SCHED_CAPACITY_SCALE; /* * if *imbalance is less than the average load per runnable task @@ -4216,9 +6234,8 @@ static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu, * a think about bumping its value to force at least one task to be * moved */ - if (*imbalance < sds->busiest_load_per_task) - return fix_small_imbalance(sds, this_cpu, imbalance); - + if (env->imbalance < busiest->load_per_task) + return fix_small_imbalance(env, sds); } /******* find_busiest_group() helpers end here *********************/ @@ -4233,159 +6250,163 @@ static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu, * Also calculates the amount of weighted load which should be moved * to restore balance. * - * @sd: The sched_domain whose busiest group is to be returned. - * @this_cpu: The cpu for which load balancing is currently being performed. - * @imbalance: Variable which stores amount of weighted load which should - * be moved to restore balance/put a group to idle. - * @idle: The idle status of this_cpu. - * @cpus: The set of CPUs under consideration for load-balancing. - * @balance: Pointer to a variable indicating if this_cpu - * is the appropriate cpu to perform load balancing at this_level. + * @env: The load balancing environment. * - * Returns: - the busiest group if imbalance exists. + * Return: - The busiest group if imbalance exists. * - If no imbalance and user has opted for power-savings balance, * return the least loaded group whose CPUs can be * put to idle by rebalancing its tasks onto our group. */ -static struct sched_group * -find_busiest_group(struct sched_domain *sd, int this_cpu, - unsigned long *imbalance, enum cpu_idle_type idle, - const struct cpumask *cpus, int *balance) +static struct sched_group *find_busiest_group(struct lb_env *env) { + struct sg_lb_stats *local, *busiest; struct sd_lb_stats sds; - memset(&sds, 0, sizeof(sds)); + init_sd_lb_stats(&sds); /* * Compute the various statistics relavent for load balancing at * this level. */ - update_sd_lb_stats(sd, this_cpu, idle, cpus, balance, &sds); + update_sd_lb_stats(env, &sds); + local = &sds.local_stat; + busiest = &sds.busiest_stat; - /* - * this_cpu is not the appropriate cpu to perform load balancing at - * this level. - */ - if (!(*balance)) - goto ret; - - if ((idle == CPU_IDLE || idle == CPU_NEWLY_IDLE) && - check_asym_packing(sd, &sds, this_cpu, imbalance)) + if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) && + check_asym_packing(env, &sds)) return sds.busiest; /* There is no busy sibling group to pull tasks from */ - if (!sds.busiest || sds.busiest_nr_running == 0) + if (!sds.busiest || busiest->sum_nr_running == 0) goto out_balanced; - sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr; + sds.avg_load = (SCHED_CAPACITY_SCALE * sds.total_load) + / sds.total_capacity; /* * If the busiest group is imbalanced the below checks don't - * work because they assumes all things are equal, which typically + * work because they assume all things are equal, which typically * isn't true due to cpus_allowed constraints and the like. */ - if (sds.group_imb) + if (busiest->group_imb) goto force_balance; /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */ - if (idle == CPU_NEWLY_IDLE && sds.this_has_capacity && - !sds.busiest_has_capacity) + if (env->idle == CPU_NEWLY_IDLE && local->group_has_free_capacity && + !busiest->group_has_free_capacity) goto force_balance; /* * If the local group is more busy than the selected busiest group * don't try and pull any tasks. */ - if (sds.this_load >= sds.max_load) + if (local->avg_load >= busiest->avg_load) goto out_balanced; /* * Don't pull any tasks if this group is already above the domain * average load. */ - if (sds.this_load >= sds.avg_load) + if (local->avg_load >= sds.avg_load) goto out_balanced; - if (idle == CPU_IDLE) { + if (env->idle == CPU_IDLE) { /* * This cpu is idle. If the busiest group load doesn't * have more tasks than the number of available cpu's and * there is no imbalance between this and busiest group * wrt to idle cpu's, it is balanced. */ - if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) && - sds.busiest_nr_running <= sds.busiest_group_weight) + if ((local->idle_cpus < busiest->idle_cpus) && + busiest->sum_nr_running <= busiest->group_weight) goto out_balanced; } else { /* * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use * imbalance_pct to be conservative. */ - if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load) + if (100 * busiest->avg_load <= + env->sd->imbalance_pct * local->avg_load) goto out_balanced; } force_balance: /* Looks like there is an imbalance. Compute it */ - calculate_imbalance(&sds, this_cpu, imbalance); + calculate_imbalance(env, &sds); return sds.busiest; out_balanced: - /* - * There is no obvious imbalance. But check if we can do some balancing - * to save power. - */ - if (check_power_save_busiest_group(&sds, this_cpu, imbalance)) - return sds.busiest; -ret: - *imbalance = 0; + env->imbalance = 0; return NULL; } /* * find_busiest_queue - find the busiest runqueue among the cpus in group. */ -static struct rq * -find_busiest_queue(struct sched_domain *sd, struct sched_group *group, - enum cpu_idle_type idle, unsigned long imbalance, - const struct cpumask *cpus) +static struct rq *find_busiest_queue(struct lb_env *env, + struct sched_group *group) { struct rq *busiest = NULL, *rq; - unsigned long max_load = 0; + unsigned long busiest_load = 0, busiest_capacity = 1; int i; - for_each_cpu(i, sched_group_cpus(group)) { - unsigned long power = power_of(i); - unsigned long capacity = DIV_ROUND_CLOSEST(power, - SCHED_POWER_SCALE); - unsigned long wl; + for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { + unsigned long capacity, capacity_factor, wl; + enum fbq_type rt; - if (!capacity) - capacity = fix_small_capacity(sd, group); + rq = cpu_rq(i); + rt = fbq_classify_rq(rq); - if (!cpumask_test_cpu(i, cpus)) + /* + * We classify groups/runqueues into three groups: + * - regular: there are !numa tasks + * - remote: there are numa tasks that run on the 'wrong' node + * - all: there is no distinction + * + * In order to avoid migrating ideally placed numa tasks, + * ignore those when there's better options. + * + * If we ignore the actual busiest queue to migrate another + * task, the next balance pass can still reduce the busiest + * queue by moving tasks around inside the node. + * + * If we cannot move enough load due to this classification + * the next pass will adjust the group classification and + * allow migration of more tasks. + * + * Both cases only affect the total convergence complexity. + */ + if (rt > env->fbq_type) continue; - rq = cpu_rq(i); + capacity = capacity_of(i); + capacity_factor = DIV_ROUND_CLOSEST(capacity, SCHED_CAPACITY_SCALE); + if (!capacity_factor) + capacity_factor = fix_small_capacity(env->sd, group); + wl = weighted_cpuload(i); /* * When comparing with imbalance, use weighted_cpuload() - * which is not scaled with the cpu power. + * which is not scaled with the cpu capacity. */ - if (capacity && rq->nr_running == 1 && wl > imbalance) + if (capacity_factor && rq->nr_running == 1 && wl > env->imbalance) continue; /* * For the load comparisons with the other cpu's, consider - * the weighted_cpuload() scaled with the cpu power, so that - * the load can be moved away from the cpu that is potentially - * running at a lower capacity. + * the weighted_cpuload() scaled with the cpu capacity, so + * that the load can be moved away from the cpu that is + * potentially running at a lower capacity. + * + * Thus we're looking for max(wl_i / capacity_i), crosswise + * multiplication to rid ourselves of the division works out + * to: wl_i * capacity_j > wl_j * capacity_i; where j is + * our previous maximum. */ - wl = (wl * SCHED_POWER_SCALE) / power; - - if (wl > max_load) { - max_load = wl; + if (wl * busiest_capacity > busiest_load * capacity) { + busiest_load = wl; + busiest_capacity = capacity; busiest = rq; } } @@ -4400,42 +6421,21 @@ find_busiest_queue(struct sched_domain *sd, struct sched_group *group, #define MAX_PINNED_INTERVAL 512 /* Working cpumask for load_balance and load_balance_newidle. */ -DEFINE_PER_CPU(cpumask_var_t, load_balance_tmpmask); +DEFINE_PER_CPU(cpumask_var_t, load_balance_mask); -static int need_active_balance(struct sched_domain *sd, int idle, - int busiest_cpu, int this_cpu) +static int need_active_balance(struct lb_env *env) { - if (idle == CPU_NEWLY_IDLE) { + struct sched_domain *sd = env->sd; + + if (env->idle == CPU_NEWLY_IDLE) { /* * ASYM_PACKING needs to force migrate tasks from busy but * higher numbered CPUs in order to pack all tasks in the * lowest numbered CPUs. */ - if ((sd->flags & SD_ASYM_PACKING) && busiest_cpu > this_cpu) + if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu) return 1; - - /* - * The only task running in a non-idle cpu can be moved to this - * cpu in an attempt to completely freeup the other CPU - * package. - * - * The package power saving logic comes from - * find_busiest_group(). If there are no imbalance, then - * f_b_g() will return NULL. However when sched_mc={1,2} then - * f_b_g() will select a group from which a running task may be - * pulled to this cpu in order to make the other package idle. - * If there is no opportunity to make a package idle and if - * there are no imbalance, then f_b_g() will return NULL and no - * action will be taken in load_balance_newidle(). - * - * Under normal task pull operation due to imbalance, there - * will be more than one task in the source run queue and - * move_tasks() will succeed. ld_moved will be true and this - * active balance code will not be triggered. - */ - if (sched_mc_power_savings < POWERSAVINGS_BALANCE_WAKEUP) - return 0; } return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2); @@ -4443,46 +6443,98 @@ static int need_active_balance(struct sched_domain *sd, int idle, static int active_load_balance_cpu_stop(void *data); +static int should_we_balance(struct lb_env *env) +{ + struct sched_group *sg = env->sd->groups; + struct cpumask *sg_cpus, *sg_mask; + int cpu, balance_cpu = -1; + + /* + * In the newly idle case, we will allow all the cpu's + * to do the newly idle load balance. + */ + if (env->idle == CPU_NEWLY_IDLE) + return 1; + + sg_cpus = sched_group_cpus(sg); + sg_mask = sched_group_mask(sg); + /* Try to find first idle cpu */ + for_each_cpu_and(cpu, sg_cpus, env->cpus) { + if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu)) + continue; + + balance_cpu = cpu; + break; + } + + if (balance_cpu == -1) + balance_cpu = group_balance_cpu(sg); + + /* + * First idle cpu or the first cpu(busiest) in this sched group + * is eligible for doing load balancing at this and above domains. + */ + return balance_cpu == env->dst_cpu; +} + /* * Check this_cpu to ensure it is balanced within domain. Attempt to move * tasks if there is an imbalance. */ static int load_balance(int this_cpu, struct rq *this_rq, struct sched_domain *sd, enum cpu_idle_type idle, - int *balance) + int *continue_balancing) { - int ld_moved, lb_flags = 0, active_balance = 0; + int ld_moved, cur_ld_moved, active_balance = 0; + struct sched_domain *sd_parent = sd->parent; struct sched_group *group; - unsigned long imbalance; struct rq *busiest; unsigned long flags; - struct cpumask *cpus = __get_cpu_var(load_balance_tmpmask); + struct cpumask *cpus = __get_cpu_var(load_balance_mask); + + struct lb_env env = { + .sd = sd, + .dst_cpu = this_cpu, + .dst_rq = this_rq, + .dst_grpmask = sched_group_cpus(sd->groups), + .idle = idle, + .loop_break = sched_nr_migrate_break, + .cpus = cpus, + .fbq_type = all, + }; + + /* + * For NEWLY_IDLE load_balancing, we don't need to consider + * other cpus in our group + */ + if (idle == CPU_NEWLY_IDLE) + env.dst_grpmask = NULL; cpumask_copy(cpus, cpu_active_mask); schedstat_inc(sd, lb_count[idle]); redo: - group = find_busiest_group(sd, this_cpu, &imbalance, idle, - cpus, balance); - - if (*balance == 0) + if (!should_we_balance(&env)) { + *continue_balancing = 0; goto out_balanced; + } + group = find_busiest_group(&env); if (!group) { schedstat_inc(sd, lb_nobusyg[idle]); goto out_balanced; } - busiest = find_busiest_queue(sd, group, idle, imbalance, cpus); + busiest = find_busiest_queue(&env, group); if (!busiest) { schedstat_inc(sd, lb_nobusyq[idle]); goto out_balanced; } - BUG_ON(busiest == this_rq); + BUG_ON(busiest == env.dst_rq); - schedstat_add(sd, lb_imbalance[idle], imbalance); + schedstat_add(sd, lb_imbalance[idle], env.imbalance); ld_moved = 0; if (busiest->nr_running > 1) { @@ -4492,35 +6544,92 @@ redo: * still unbalanced. ld_moved simply stays zero, so it is * correctly treated as an imbalance. */ - lb_flags |= LBF_ALL_PINNED; + env.flags |= LBF_ALL_PINNED; + env.src_cpu = busiest->cpu; + env.src_rq = busiest; + env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running); + +more_balance: local_irq_save(flags); - double_rq_lock(this_rq, busiest); - ld_moved = move_tasks(this_rq, this_cpu, busiest, - imbalance, sd, idle, &lb_flags); - double_rq_unlock(this_rq, busiest); + double_rq_lock(env.dst_rq, busiest); + + /* + * cur_ld_moved - load moved in current iteration + * ld_moved - cumulative load moved across iterations + */ + cur_ld_moved = move_tasks(&env); + ld_moved += cur_ld_moved; + double_rq_unlock(env.dst_rq, busiest); local_irq_restore(flags); /* * some other cpu did the load balance for us. */ - if (ld_moved && this_cpu != smp_processor_id()) - resched_cpu(this_cpu); + if (cur_ld_moved && env.dst_cpu != smp_processor_id()) + resched_cpu(env.dst_cpu); - if (lb_flags & LBF_ABORT) - goto out_balanced; + if (env.flags & LBF_NEED_BREAK) { + env.flags &= ~LBF_NEED_BREAK; + goto more_balance; + } - if (lb_flags & LBF_NEED_BREAK) { - lb_flags += LBF_HAD_BREAK - LBF_NEED_BREAK; - if (lb_flags & LBF_ABORT) - goto out_balanced; - goto redo; + /* + * Revisit (affine) tasks on src_cpu that couldn't be moved to + * us and move them to an alternate dst_cpu in our sched_group + * where they can run. The upper limit on how many times we + * iterate on same src_cpu is dependent on number of cpus in our + * sched_group. + * + * This changes load balance semantics a bit on who can move + * load to a given_cpu. In addition to the given_cpu itself + * (or a ilb_cpu acting on its behalf where given_cpu is + * nohz-idle), we now have balance_cpu in a position to move + * load to given_cpu. In rare situations, this may cause + * conflicts (balance_cpu and given_cpu/ilb_cpu deciding + * _independently_ and at _same_ time to move some load to + * given_cpu) causing exceess load to be moved to given_cpu. + * This however should not happen so much in practice and + * moreover subsequent load balance cycles should correct the + * excess load moved. + */ + if ((env.flags & LBF_DST_PINNED) && env.imbalance > 0) { + + /* Prevent to re-select dst_cpu via env's cpus */ + cpumask_clear_cpu(env.dst_cpu, env.cpus); + + env.dst_rq = cpu_rq(env.new_dst_cpu); + env.dst_cpu = env.new_dst_cpu; + env.flags &= ~LBF_DST_PINNED; + env.loop = 0; + env.loop_break = sched_nr_migrate_break; + + /* + * Go back to "more_balance" rather than "redo" since we + * need to continue with same src_cpu. + */ + goto more_balance; + } + + /* + * We failed to reach balance because of affinity. + */ + if (sd_parent) { + int *group_imbalance = &sd_parent->groups->sgc->imbalance; + + if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) { + *group_imbalance = 1; + } else if (*group_imbalance) + *group_imbalance = 0; } /* All tasks on this runqueue were pinned by CPU affinity */ - if (unlikely(lb_flags & LBF_ALL_PINNED)) { + if (unlikely(env.flags & LBF_ALL_PINNED)) { cpumask_clear_cpu(cpu_of(busiest), cpus); - if (!cpumask_empty(cpus)) + if (!cpumask_empty(cpus)) { + env.loop = 0; + env.loop_break = sched_nr_migrate_break; goto redo; + } goto out_balanced; } } @@ -4536,7 +6645,7 @@ redo: if (idle != CPU_NEWLY_IDLE) sd->nr_balance_failed++; - if (need_active_balance(sd, idle, cpu_of(busiest), this_cpu)) { + if (need_active_balance(&env)) { raw_spin_lock_irqsave(&busiest->lock, flags); /* don't kick the active_load_balance_cpu_stop, @@ -4547,7 +6656,7 @@ redo: tsk_cpus_allowed(busiest->curr))) { raw_spin_unlock_irqrestore(&busiest->lock, flags); - lb_flags |= LBF_ALL_PINNED; + env.flags |= LBF_ALL_PINNED; goto out_one_pinned; } @@ -4563,10 +6672,11 @@ redo: } raw_spin_unlock_irqrestore(&busiest->lock, flags); - if (active_balance) + if (active_balance) { stop_one_cpu_nowait(cpu_of(busiest), active_load_balance_cpu_stop, busiest, &busiest->active_balance_work); + } /* * We've kicked active balancing, reset the failure @@ -4600,7 +6710,7 @@ out_balanced: out_one_pinned: /* tune up the balancing interval */ - if (((lb_flags & LBF_ALL_PINNED) && + if (((env.flags & LBF_ALL_PINNED) && sd->balance_interval < MAX_PINNED_INTERVAL) || (sd->balance_interval < sd->max_interval)) sd->balance_interval *= 2; @@ -4610,60 +6720,135 @@ out: return ld_moved; } +static inline unsigned long +get_sd_balance_interval(struct sched_domain *sd, int cpu_busy) +{ + unsigned long interval = sd->balance_interval; + + if (cpu_busy) + interval *= sd->busy_factor; + + /* scale ms to jiffies */ + interval = msecs_to_jiffies(interval); + interval = clamp(interval, 1UL, max_load_balance_interval); + + return interval; +} + +static inline void +update_next_balance(struct sched_domain *sd, int cpu_busy, unsigned long *next_balance) +{ + unsigned long interval, next; + + interval = get_sd_balance_interval(sd, cpu_busy); + next = sd->last_balance + interval; + + if (time_after(*next_balance, next)) + *next_balance = next; +} + /* * idle_balance is called by schedule() if this_cpu is about to become * idle. Attempts to pull tasks from other CPUs. */ -void idle_balance(int this_cpu, struct rq *this_rq) +static int idle_balance(struct rq *this_rq) { + unsigned long next_balance = jiffies + HZ; + int this_cpu = this_rq->cpu; struct sched_domain *sd; int pulled_task = 0; - unsigned long next_balance = jiffies + HZ; + u64 curr_cost = 0; - this_rq->idle_stamp = this_rq->clock; + idle_enter_fair(this_rq); - if (this_rq->avg_idle < sysctl_sched_migration_cost) - return; + /* + * We must set idle_stamp _before_ calling idle_balance(), such that we + * measure the duration of idle_balance() as idle time. + */ + this_rq->idle_stamp = rq_clock(this_rq); + + if (this_rq->avg_idle < sysctl_sched_migration_cost) { + rcu_read_lock(); + sd = rcu_dereference_check_sched_domain(this_rq->sd); + if (sd) + update_next_balance(sd, 0, &next_balance); + rcu_read_unlock(); + + goto out; + } /* * Drop the rq->lock, but keep IRQ/preempt disabled. */ raw_spin_unlock(&this_rq->lock); - update_shares(this_cpu); + update_blocked_averages(this_cpu); rcu_read_lock(); for_each_domain(this_cpu, sd) { - unsigned long interval; - int balance = 1; + int continue_balancing = 1; + u64 t0, domain_cost; if (!(sd->flags & SD_LOAD_BALANCE)) continue; + if (this_rq->avg_idle < curr_cost + sd->max_newidle_lb_cost) { + update_next_balance(sd, 0, &next_balance); + break; + } + if (sd->flags & SD_BALANCE_NEWIDLE) { - /* If we've pulled tasks over stop searching: */ + t0 = sched_clock_cpu(this_cpu); + pulled_task = load_balance(this_cpu, this_rq, - sd, CPU_NEWLY_IDLE, &balance); + sd, CPU_NEWLY_IDLE, + &continue_balancing); + + domain_cost = sched_clock_cpu(this_cpu) - t0; + if (domain_cost > sd->max_newidle_lb_cost) + sd->max_newidle_lb_cost = domain_cost; + + curr_cost += domain_cost; } - interval = msecs_to_jiffies(sd->balance_interval); - if (time_after(next_balance, sd->last_balance + interval)) - next_balance = sd->last_balance + interval; - if (pulled_task) { - this_rq->idle_stamp = 0; + update_next_balance(sd, 0, &next_balance); + + /* + * Stop searching for tasks to pull if there are + * now runnable tasks on this rq. + */ + if (pulled_task || this_rq->nr_running > 0) break; - } } rcu_read_unlock(); raw_spin_lock(&this_rq->lock); - if (pulled_task || time_after(jiffies, this_rq->next_balance)) { - /* - * We are going idle. next_balance may be set based on - * a busy processor. So reset next_balance. - */ + if (curr_cost > this_rq->max_idle_balance_cost) + this_rq->max_idle_balance_cost = curr_cost; + + /* + * While browsing the domains, we released the rq lock, a task could + * have been enqueued in the meantime. Since we're not going idle, + * pretend we pulled a task. + */ + if (this_rq->cfs.h_nr_running && !pulled_task) + pulled_task = 1; + +out: + /* Move the next balance forward */ + if (time_after(this_rq->next_balance, next_balance)) this_rq->next_balance = next_balance; + + /* Is there a task of a high priority class? */ + if (this_rq->nr_running != this_rq->cfs.h_nr_running) + pulled_task = -1; + + if (pulled_task) { + idle_exit_fair(this_rq); + this_rq->idle_stamp = 0; } + + return pulled_task; } /* @@ -4710,10 +6895,18 @@ static int active_load_balance_cpu_stop(void *data) } if (likely(sd)) { + struct lb_env env = { + .sd = sd, + .dst_cpu = target_cpu, + .dst_rq = target_rq, + .src_cpu = busiest_rq->cpu, + .src_rq = busiest_rq, + .idle = CPU_IDLE, + }; + schedstat_inc(sd, alb_count); - if (move_one_task(target_rq, target_cpu, busiest_rq, - sd, CPU_IDLE)) + if (move_one_task(&env)) schedstat_inc(sd, alb_pushed); else schedstat_inc(sd, alb_failed); @@ -4726,7 +6919,12 @@ out_unlock: return 0; } -#ifdef CONFIG_NO_HZ +static inline int on_null_domain(struct rq *rq) +{ + return unlikely(!rcu_dereference_sched(rq->sd)); +} + +#ifdef CONFIG_NO_HZ_COMMON /* * idle load balancing details * - When one of the busy CPUs notice that there may be an idle rebalancing @@ -4739,117 +6937,28 @@ static struct { unsigned long next_balance; /* in jiffy units */ } nohz ____cacheline_aligned; -#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) -/** - * lowest_flag_domain - Return lowest sched_domain containing flag. - * @cpu: The cpu whose lowest level of sched domain is to - * be returned. - * @flag: The flag to check for the lowest sched_domain - * for the given cpu. - * - * Returns the lowest sched_domain of a cpu which contains the given flag. - */ -static inline struct sched_domain *lowest_flag_domain(int cpu, int flag) -{ - struct sched_domain *sd; - - for_each_domain(cpu, sd) - if (sd->flags & flag) - break; - - return sd; -} - -/** - * for_each_flag_domain - Iterates over sched_domains containing the flag. - * @cpu: The cpu whose domains we're iterating over. - * @sd: variable holding the value of the power_savings_sd - * for cpu. - * @flag: The flag to filter the sched_domains to be iterated. - * - * Iterates over all the scheduler domains for a given cpu that has the 'flag' - * set, starting from the lowest sched_domain to the highest. - */ -#define for_each_flag_domain(cpu, sd, flag) \ - for (sd = lowest_flag_domain(cpu, flag); \ - (sd && (sd->flags & flag)); sd = sd->parent) - -/** - * find_new_ilb - Finds the optimum idle load balancer for nomination. - * @cpu: The cpu which is nominating a new idle_load_balancer. - * - * Returns: Returns the id of the idle load balancer if it exists, - * Else, returns >= nr_cpu_ids. - * - * This algorithm picks the idle load balancer such that it belongs to a - * semi-idle powersavings sched_domain. The idea is to try and avoid - * completely idle packages/cores just for the purpose of idle load balancing - * when there are other idle cpu's which are better suited for that job. - */ -static int find_new_ilb(int cpu) +static inline int find_new_ilb(void) { int ilb = cpumask_first(nohz.idle_cpus_mask); - struct sched_group *ilbg; - struct sched_domain *sd; - - /* - * Have idle load balancer selection from semi-idle packages only - * when power-aware load balancing is enabled - */ - if (!(sched_smt_power_savings || sched_mc_power_savings)) - goto out_done; - - /* - * Optimize for the case when we have no idle CPUs or only one - * idle CPU. Don't walk the sched_domain hierarchy in such cases - */ - if (cpumask_weight(nohz.idle_cpus_mask) < 2) - goto out_done; - - rcu_read_lock(); - for_each_flag_domain(cpu, sd, SD_POWERSAVINGS_BALANCE) { - ilbg = sd->groups; - - do { - if (ilbg->group_weight != - atomic_read(&ilbg->sgp->nr_busy_cpus)) { - ilb = cpumask_first_and(nohz.idle_cpus_mask, - sched_group_cpus(ilbg)); - goto unlock; - } - - ilbg = ilbg->next; - } while (ilbg != sd->groups); - } -unlock: - rcu_read_unlock(); - -out_done: if (ilb < nr_cpu_ids && idle_cpu(ilb)) return ilb; return nr_cpu_ids; } -#else /* (CONFIG_SCHED_MC || CONFIG_SCHED_SMT) */ -static inline int find_new_ilb(int call_cpu) -{ - return nr_cpu_ids; -} -#endif /* * Kick a CPU to do the nohz balancing, if it is time for it. We pick the * nohz_load_balancer CPU (if there is one) otherwise fallback to any idle * CPU (if there is one). */ -static void nohz_balancer_kick(int cpu) +static void nohz_balancer_kick(void) { int ilb_cpu; nohz.next_balance++; - ilb_cpu = find_new_ilb(cpu); + ilb_cpu = find_new_ilb(); if (ilb_cpu >= nr_cpu_ids) return; @@ -4866,11 +6975,16 @@ static void nohz_balancer_kick(int cpu) return; } -static inline void clear_nohz_tick_stopped(int cpu) +static inline void nohz_balance_exit_idle(int cpu) { if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) { - cpumask_clear_cpu(cpu, nohz.idle_cpus_mask); - atomic_dec(&nohz.nr_cpus); + /* + * Completely isolated CPUs don't ever set, so we must test. + */ + if (likely(cpumask_test_cpu(cpu, nohz.idle_cpus_mask))) { + cpumask_clear_cpu(cpu, nohz.idle_cpus_mask); + atomic_dec(&nohz.nr_cpus); + } clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); } } @@ -4880,13 +6994,15 @@ static inline void set_cpu_sd_state_busy(void) struct sched_domain *sd; int cpu = smp_processor_id(); - if (!test_bit(NOHZ_IDLE, nohz_flags(cpu))) - return; - clear_bit(NOHZ_IDLE, nohz_flags(cpu)); - rcu_read_lock(); - for_each_domain(cpu, sd) - atomic_inc(&sd->groups->sgp->nr_busy_cpus); + sd = rcu_dereference(per_cpu(sd_busy, cpu)); + + if (!sd || !sd->nohz_idle) + goto unlock; + sd->nohz_idle = 0; + + atomic_inc(&sd->groups->sgc->nr_busy_cpus); +unlock: rcu_read_unlock(); } @@ -4895,47 +7011,50 @@ void set_cpu_sd_state_idle(void) struct sched_domain *sd; int cpu = smp_processor_id(); - if (test_bit(NOHZ_IDLE, nohz_flags(cpu))) - return; - set_bit(NOHZ_IDLE, nohz_flags(cpu)); - rcu_read_lock(); - for_each_domain(cpu, sd) - atomic_dec(&sd->groups->sgp->nr_busy_cpus); + sd = rcu_dereference(per_cpu(sd_busy, cpu)); + + if (!sd || sd->nohz_idle) + goto unlock; + sd->nohz_idle = 1; + + atomic_dec(&sd->groups->sgc->nr_busy_cpus); +unlock: rcu_read_unlock(); } /* - * This routine will record that this cpu is going idle with tick stopped. + * This routine will record that the cpu is going idle with tick stopped. * This info will be used in performing idle load balancing in the future. */ -void select_nohz_load_balancer(int stop_tick) +void nohz_balance_enter_idle(int cpu) { - int cpu = smp_processor_id(); - /* * If this cpu is going down, then nothing needs to be done. */ if (!cpu_active(cpu)) return; - if (stop_tick) { - if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu))) - return; + if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu))) + return; - cpumask_set_cpu(cpu, nohz.idle_cpus_mask); - atomic_inc(&nohz.nr_cpus); - set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); - } - return; + /* + * If we're a completely isolated CPU, we don't play. + */ + if (on_null_domain(cpu_rq(cpu))) + return; + + cpumask_set_cpu(cpu, nohz.idle_cpus_mask); + atomic_inc(&nohz.nr_cpus); + set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)); } -static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb, +static int sched_ilb_notifier(struct notifier_block *nfb, unsigned long action, void *hcpu) { switch (action & ~CPU_TASKS_FROZEN) { case CPU_DYING: - clear_nohz_tick_stopped(smp_processor_id()); + nohz_balance_exit_idle(smp_processor_id()); return NOTIFY_OK; default: return NOTIFY_DONE; @@ -4945,8 +7064,6 @@ static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb, static DEFINE_SPINLOCK(balancing); -static unsigned long __read_mostly max_load_balance_interval = HZ/10; - /* * Scale the max load_balance interval with the number of CPUs in the system. * This trades load-balance latency on larger machines for less cross talk. @@ -4960,50 +7077,69 @@ void update_max_interval(void) * It checks each scheduling domain to see if it is due to be balanced, * and initiates a balancing operation if so. * - * Balancing parameters are set up in arch_init_sched_domains. + * Balancing parameters are set up in init_sched_domains. */ -static void rebalance_domains(int cpu, enum cpu_idle_type idle) +static void rebalance_domains(struct rq *rq, enum cpu_idle_type idle) { - int balance = 1; - struct rq *rq = cpu_rq(cpu); + int continue_balancing = 1; + int cpu = rq->cpu; unsigned long interval; struct sched_domain *sd; /* Earliest time when we have to do rebalance again */ unsigned long next_balance = jiffies + 60*HZ; int update_next_balance = 0; - int need_serialize; + int need_serialize, need_decay = 0; + u64 max_cost = 0; - update_shares(cpu); + update_blocked_averages(cpu); rcu_read_lock(); for_each_domain(cpu, sd) { + /* + * Decay the newidle max times here because this is a regular + * visit to all the domains. Decay ~1% per second. + */ + if (time_after(jiffies, sd->next_decay_max_lb_cost)) { + sd->max_newidle_lb_cost = + (sd->max_newidle_lb_cost * 253) / 256; + sd->next_decay_max_lb_cost = jiffies + HZ; + need_decay = 1; + } + max_cost += sd->max_newidle_lb_cost; + if (!(sd->flags & SD_LOAD_BALANCE)) continue; - interval = sd->balance_interval; - if (idle != CPU_IDLE) - interval *= sd->busy_factor; + /* + * Stop the load balance at this level. There is another + * CPU in our sched group which is doing load balancing more + * actively. + */ + if (!continue_balancing) { + if (need_decay) + continue; + break; + } - /* scale ms to jiffies */ - interval = msecs_to_jiffies(interval); - interval = clamp(interval, 1UL, max_load_balance_interval); + interval = get_sd_balance_interval(sd, idle != CPU_IDLE); need_serialize = sd->flags & SD_SERIALIZE; - if (need_serialize) { if (!spin_trylock(&balancing)) goto out; } if (time_after_eq(jiffies, sd->last_balance + interval)) { - if (load_balance(cpu, rq, sd, idle, &balance)) { + if (load_balance(cpu, rq, sd, idle, &continue_balancing)) { /* - * We've pulled tasks over so either we're no - * longer idle. + * The LBF_DST_PINNED logic could have changed + * env->dst_cpu, so we can't know our idle + * state even if we migrated tasks. Update it. */ - idle = CPU_NOT_IDLE; + idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE; } sd->last_balance = jiffies; + interval = get_sd_balance_interval(sd, idle != CPU_IDLE); } if (need_serialize) spin_unlock(&balancing); @@ -5012,14 +7148,14 @@ out: next_balance = sd->last_balance + interval; update_next_balance = 1; } - + } + if (need_decay) { /* - * Stop the load balance at this level. There is another - * CPU in our sched group which is doing load balancing more - * actively. + * Ensure the rq-wide value also decays but keep it at a + * reasonable floor to avoid funnies with rq->avg_idle. */ - if (!balance) - break; + rq->max_idle_balance_cost = + max((u64)sysctl_sched_migration_cost, max_cost); } rcu_read_unlock(); @@ -5032,14 +7168,14 @@ out: rq->next_balance = next_balance; } -#ifdef CONFIG_NO_HZ +#ifdef CONFIG_NO_HZ_COMMON /* - * In CONFIG_NO_HZ case, the idle balance kickee will do the + * In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the * rebalancing for all the cpus for whom scheduler ticks are stopped. */ -static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) +static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { - struct rq *this_rq = cpu_rq(this_cpu); + int this_cpu = this_rq->cpu; struct rq *rq; int balance_cpu; @@ -5059,14 +7195,20 @@ static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) if (need_resched()) break; - raw_spin_lock_irq(&this_rq->lock); - update_rq_clock(this_rq); - update_cpu_load(this_rq); - raw_spin_unlock_irq(&this_rq->lock); + rq = cpu_rq(balance_cpu); - rebalance_domains(balance_cpu, CPU_IDLE); + /* + * If time for next balance is due, + * do the balance. + */ + if (time_after_eq(jiffies, rq->next_balance)) { + raw_spin_lock_irq(&rq->lock); + update_rq_clock(rq); + update_idle_cpu_load(rq); + raw_spin_unlock_irq(&rq->lock); + rebalance_domains(rq, CPU_IDLE); + } - rq = cpu_rq(balance_cpu); if (time_after(this_rq->next_balance, rq->next_balance)) this_rq->next_balance = rq->next_balance; } @@ -5080,16 +7222,18 @@ end: * of an idle cpu is the system. * - This rq has more than one task. * - At any scheduler domain level, this cpu's scheduler group has multiple - * busy cpu's exceeding the group's power. + * busy cpu's exceeding the group's capacity. * - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler * domain span are idle. */ -static inline int nohz_kick_needed(struct rq *rq, int cpu) +static inline int nohz_kick_needed(struct rq *rq) { unsigned long now = jiffies; struct sched_domain *sd; + struct sched_group_capacity *sgc; + int nr_busy, cpu = rq->cpu; - if (unlikely(idle_cpu(cpu))) + if (unlikely(rq->idle_balance)) return 0; /* @@ -5097,7 +7241,7 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu) * busy tick after returning from idle, we will update the busy stats. */ set_cpu_sd_state_busy(); - clear_nohz_tick_stopped(cpu); + nohz_balance_exit_idle(cpu); /* * None are in tickless mode and hence no need for NOHZ idle load @@ -5113,22 +7257,22 @@ static inline int nohz_kick_needed(struct rq *rq, int cpu) goto need_kick; rcu_read_lock(); - for_each_domain(cpu, sd) { - struct sched_group *sg = sd->groups; - struct sched_group_power *sgp = sg->sgp; - int nr_busy = atomic_read(&sgp->nr_busy_cpus); + sd = rcu_dereference(per_cpu(sd_busy, cpu)); - if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1) - goto need_kick_unlock; + if (sd) { + sgc = sd->groups->sgc; + nr_busy = atomic_read(&sgc->nr_busy_cpus); - if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight - && (cpumask_first_and(nohz.idle_cpus_mask, - sched_domain_span(sd)) < cpu)) + if (nr_busy > 1) goto need_kick_unlock; - - if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING))) - break; } + + sd = rcu_dereference(per_cpu(sd_asym, cpu)); + + if (sd && (cpumask_first_and(nohz.idle_cpus_mask, + sched_domain_span(sd)) < cpu)) + goto need_kick_unlock; + rcu_read_unlock(); return 0; @@ -5138,7 +7282,7 @@ need_kick: return 1; } #else -static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { } +static void nohz_idle_balance(struct rq *this_rq, enum cpu_idle_type idle) { } #endif /* @@ -5147,38 +7291,34 @@ static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { } */ static void run_rebalance_domains(struct softirq_action *h) { - int this_cpu = smp_processor_id(); - struct rq *this_rq = cpu_rq(this_cpu); + struct rq *this_rq = this_rq(); enum cpu_idle_type idle = this_rq->idle_balance ? CPU_IDLE : CPU_NOT_IDLE; - rebalance_domains(this_cpu, idle); + rebalance_domains(this_rq, idle); /* * If this cpu has a pending nohz_balance_kick, then do the * balancing on behalf of the other idle cpus whose ticks are * stopped. */ - nohz_idle_balance(this_cpu, idle); -} - -static inline int on_null_domain(int cpu) -{ - return !rcu_dereference_sched(cpu_rq(cpu)->sd); + nohz_idle_balance(this_rq, idle); } /* * Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing. */ -void trigger_load_balance(struct rq *rq, int cpu) +void trigger_load_balance(struct rq *rq) { /* Don't need to rebalance while attached to NULL domain */ - if (time_after_eq(jiffies, rq->next_balance) && - likely(!on_null_domain(cpu))) + if (unlikely(on_null_domain(rq))) + return; + + if (time_after_eq(jiffies, rq->next_balance)) raise_softirq(SCHED_SOFTIRQ); -#ifdef CONFIG_NO_HZ - if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu))) - nohz_balancer_kick(cpu); +#ifdef CONFIG_NO_HZ_COMMON + if (nohz_kick_needed(rq)) + nohz_balancer_kick(); #endif } @@ -5190,6 +7330,9 @@ static void rq_online_fair(struct rq *rq) static void rq_offline_fair(struct rq *rq) { update_sysctl(); + + /* Ensure any throttled groups are reachable by pick_next_task */ + unthrottle_offline_cfs_rqs(rq); } #endif /* CONFIG_SMP */ @@ -5206,6 +7349,11 @@ static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued) cfs_rq = cfs_rq_of(se); entity_tick(cfs_rq, se, queued); } + + if (numabalancing_enabled) + task_tick_numa(rq, curr); + + update_rq_runnable_avg(rq, 1); } /* @@ -5228,11 +7376,15 @@ static void task_fork_fair(struct task_struct *p) cfs_rq = task_cfs_rq(current); curr = cfs_rq->curr; - if (unlikely(task_cpu(p) != this_cpu)) { - rcu_read_lock(); - __set_task_cpu(p, this_cpu); - rcu_read_unlock(); - } + /* + * Not only the cpu but also the task_group of the parent might have + * been changed after parent->se.parent,cfs_rq were copied to + * child->se.parent,cfs_rq. So call __set_task_cpu() to make those + * of child point to valid ones. + */ + rcu_read_lock(); + __set_task_cpu(p, this_cpu); + rcu_read_unlock(); update_curr(cfs_rq); @@ -5282,15 +7434,15 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p) struct cfs_rq *cfs_rq = cfs_rq_of(se); /* - * Ensure the task's vruntime is normalized, so that when its + * Ensure the task's vruntime is normalized, so that when it's * switched back to the fair class the enqueue_entity(.flags=0) will * do the right thing. * - * If it was on_rq, then the dequeue_entity(.flags=0) will already - * have normalized the vruntime, if it was !on_rq, then only when + * If it's on_rq, then the dequeue_entity(.flags=0) will already + * have normalized the vruntime, if it's !on_rq, then only when * the task is sleeping will it still have non-normalized vruntime. */ - if (!se->on_rq && p->state != TASK_RUNNING) { + if (!p->on_rq && p->state != TASK_RUNNING) { /* * Fix up our vruntime so that the current sleep doesn't * cause 'unlimited' sleep bonus. @@ -5298,6 +7450,18 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p) place_entity(cfs_rq, se, 0); se->vruntime -= cfs_rq->min_vruntime; } + +#ifdef CONFIG_SMP + /* + * Remove our load from contribution when we leave sched_fair + * and ensure we don't carry in an old decay_count if we + * switch back. + */ + if (se->avg.decay_count) { + __synchronize_entity_decay(se); + subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib); + } +#endif } /* @@ -5305,7 +7469,15 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p) */ static void switched_to_fair(struct rq *rq, struct task_struct *p) { - if (!p->se.on_rq) + struct sched_entity *se = &p->se; +#ifdef CONFIG_FAIR_GROUP_SCHED + /* + * Since the real-depth could have been changed (only FAIR + * class maintain depth value), reset depth properly. + */ + se->depth = se->parent ? se->parent->depth + 1 : 0; +#endif + if (!se->on_rq) return; /* @@ -5340,16 +7512,22 @@ static void set_curr_task_fair(struct rq *rq) void init_cfs_rq(struct cfs_rq *cfs_rq) { cfs_rq->tasks_timeline = RB_ROOT; - INIT_LIST_HEAD(&cfs_rq->tasks); cfs_rq->min_vruntime = (u64)(-(1LL << 20)); #ifndef CONFIG_64BIT cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime; #endif +#ifdef CONFIG_SMP + atomic64_set(&cfs_rq->decay_counter, 1); + atomic_long_set(&cfs_rq->removed_load, 0); +#endif } #ifdef CONFIG_FAIR_GROUP_SCHED static void task_move_group_fair(struct task_struct *p, int on_rq) { + struct sched_entity *se = &p->se; + struct cfs_rq *cfs_rq; + /* * If the task was not on the rq at the time of this cgroup movement * it must have been asleep, sleeping tasks keep their ->vruntime @@ -5375,14 +7553,26 @@ static void task_move_group_fair(struct task_struct *p, int on_rq) * To prevent boost or penalty in the new cfs_rq caused by delta * min_vruntime between the two cfs_rqs, we skip vruntime adjustment. */ - if (!on_rq && (!p->se.sum_exec_runtime || p->state == TASK_WAKING)) + if (!on_rq && (!se->sum_exec_runtime || p->state == TASK_WAKING)) on_rq = 1; if (!on_rq) - p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime; + se->vruntime -= cfs_rq_of(se)->min_vruntime; set_task_rq(p, task_cpu(p)); - if (!on_rq) - p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime; + se->depth = se->parent ? se->parent->depth + 1 : 0; + if (!on_rq) { + cfs_rq = cfs_rq_of(se); + se->vruntime += cfs_rq->min_vruntime; +#ifdef CONFIG_SMP + /* + * migrate_task_rq_fair() will have removed our previous + * contribution, but we must synchronize for ongoing future + * decay. + */ + se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter); + cfs_rq->blocked_load_avg += se->avg.load_avg_contrib; +#endif + } } void free_fair_sched_group(struct task_group *tg) @@ -5467,10 +7657,6 @@ void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, cfs_rq->tg = tg; cfs_rq->rq = rq; -#ifdef CONFIG_SMP - /* allow initial update_cfs_load() to truncate */ - cfs_rq->load_stamp = 1; -#endif init_cfs_rq_runtime(cfs_rq); tg->cfs_rq[cpu] = cfs_rq; @@ -5480,13 +7666,17 @@ void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq, if (!se) return; - if (!parent) + if (!parent) { se->cfs_rq = &rq->cfs; - else + se->depth = 0; + } else { se->cfs_rq = parent->my_q; + se->depth = parent->depth + 1; + } se->my_q = cfs_rq; - update_load_set(&se->load, 0); + /* guarantee group entities always have weight */ + update_load_set(&se->load, NICE_0_LOAD); se->parent = parent; } @@ -5517,6 +7707,9 @@ int sched_group_set_shares(struct task_group *tg, unsigned long shares) se = tg->se[i]; /* Propagate contribution to hierarchy */ raw_spin_lock_irqsave(&rq->lock, flags); + + /* Possible calls to update_curr() need rq clock */ + update_rq_clock(rq); for_each_sched_entity(se) update_cfs_shares(group_cfs_rq(se)); raw_spin_unlock_irqrestore(&rq->lock, flags); @@ -5550,7 +7743,7 @@ static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task * idle runqueue: */ if (rq->cfs.load.weight) - rr_interval = NS_TO_JIFFIES(sched_slice(&rq->cfs, se)); + rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se)); return rr_interval; } @@ -5572,6 +7765,7 @@ const struct sched_class fair_sched_class = { #ifdef CONFIG_SMP .select_task_rq = select_task_rq_fair, + .migrate_task_rq = migrate_task_rq_fair, .rq_online = rq_online_fair, .rq_offline = rq_offline_fair, @@ -5611,7 +7805,8 @@ __init void init_sched_fair_class(void) #ifdef CONFIG_SMP open_softirq(SCHED_SOFTIRQ, run_rebalance_domains); -#ifdef CONFIG_NO_HZ +#ifdef CONFIG_NO_HZ_COMMON + nohz.next_balance = jiffies; zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT); cpu_notifier(sched_ilb_notifier, 0); #endif |