diff options
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 703 |
1 files changed, 514 insertions, 189 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index e64b0794060..7e9bd0b1fa9 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -322,13 +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) @@ -336,17 +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) { @@ -360,8 +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--; @@ -426,12 +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; @@ -819,14 +802,6 @@ 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; -/* - * After skipping a page migration on a shared page, skip N more numa page - * migrations unconditionally. This reduces the number of NUMA migrations - * in shared memory workloads, and has the effect of pulling tasks towards - * where their memory lives, over pulling the memory towards the task. - */ -unsigned int sysctl_numa_balancing_migrate_deferred = 16; - static unsigned int task_nr_scan_windows(struct task_struct *p) { unsigned long rss = 0; @@ -872,15 +847,6 @@ static unsigned int task_scan_max(struct task_struct *p) return max(smin, smax); } -/* - * Once a preferred node is selected the scheduler balancer will prefer moving - * a task to that node for sysctl_numa_balancing_settle_count number of PTE - * scans. This will give the process the chance to accumulate more faults on - * the preferred node but still allow the scheduler to move the task again if - * the nodes CPUs are overloaded. - */ -unsigned int sysctl_numa_balancing_settle_count __read_mostly = 4; - static void account_numa_enqueue(struct rq *rq, struct task_struct *p) { rq->nr_numa_running += (p->numa_preferred_nid != -1); @@ -902,10 +868,26 @@ struct numa_group { 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; @@ -913,16 +895,16 @@ pid_t task_numa_group_id(struct task_struct *p) static inline int task_faults_idx(int nid, int priv) { - return 2 * nid + 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) + if (!p->numa_faults_memory) return 0; - return p->numa_faults[task_faults_idx(nid, 0)] + - p->numa_faults[task_faults_idx(nid, 1)]; + 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) @@ -930,7 +912,14 @@ static inline unsigned long group_faults(struct task_struct *p, int nid) if (!p->numa_group) return 0; - return p->numa_group->faults[2*nid] + p->numa_group->faults[2*nid+1]; + 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)]; } /* @@ -943,7 +932,7 @@ static inline unsigned long task_weight(struct task_struct *p, int nid) { unsigned long total_faults; - if (!p->numa_faults) + if (!p->numa_faults_memory) return 0; total_faults = p->total_numa_faults; @@ -962,6 +951,69 @@ static inline unsigned long group_weight(struct task_struct *p, int nid) 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); @@ -1023,7 +1075,7 @@ struct task_numa_env { struct numa_stats src_stats, dst_stats; - int imbalance_pct, idx; + int imbalance_pct; struct task_struct *best_task; long best_imp; @@ -1211,7 +1263,7 @@ static int task_numa_migrate(struct task_struct *p) * elsewhere, so there is no point in (re)trying. */ if (unlikely(!sd)) { - p->numa_preferred_nid = cpu_to_node(task_cpu(p)); + p->numa_preferred_nid = task_node(p); return -EINVAL; } @@ -1258,11 +1310,15 @@ static int task_numa_migrate(struct task_struct *p) p->numa_scan_period = task_scan_min(p); if (env.best_task == NULL) { - int ret = migrate_task_to(p, env.best_cpu); + 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; } @@ -1271,14 +1327,14 @@ static int task_numa_migrate(struct task_struct *p) static void numa_migrate_preferred(struct task_struct *p) { /* This task has no NUMA fault statistics yet */ - if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults)) + if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults_memory)) return; /* Periodically retry migrating the task to the preferred node */ p->numa_migrate_retry = jiffies + HZ; /* Success if task is already running on preferred CPU */ - if (cpu_to_node(task_cpu(p)) == p->numa_preferred_nid) + if (task_node(p) == p->numa_preferred_nid) return; /* Otherwise, try migrate to a CPU on the preferred node */ @@ -1286,6 +1342,38 @@ static void numa_migrate_preferred(struct task_struct *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 @@ -1350,7 +1438,6 @@ static void update_task_scan_period(struct task_struct *p, * scanning faster if shared accesses dominate as it may * simply bounce migrations uselessly */ - period_slot = DIV_ROUND_UP(diff, NUMA_PERIOD_SLOTS); ratio = DIV_ROUND_UP(private * NUMA_PERIOD_SLOTS, (private + shared)); diff = (diff * ratio) / NUMA_PERIOD_SLOTS; } @@ -1360,11 +1447,41 @@ static void update_task_scan_period(struct task_struct *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); @@ -1373,6 +1490,10 @@ static void task_numa_placement(struct task_struct *p) 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; @@ -1384,24 +1505,37 @@ static void task_numa_placement(struct task_struct *p) unsigned long faults = 0, group_faults = 0; int priv, i; - for (priv = 0; priv < 2; priv++) { - long diff; + for (priv = 0; priv < NR_NUMA_HINT_FAULT_TYPES; priv++) { + long diff, f_diff, f_weight; i = task_faults_idx(nid, priv); - diff = -p->numa_faults[i]; /* Decay existing window, copy faults since last scan */ - p->numa_faults[i] >>= 1; - p->numa_faults[i] += p->numa_faults_buffer[i]; - fault_types[priv] += p->numa_faults_buffer[i]; - p->numa_faults_buffer[i] = 0; + 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; - faults += p->numa_faults[i]; - diff += p->numa_faults[i]; + /* + * 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]; } @@ -1421,6 +1555,7 @@ static void task_numa_placement(struct task_struct *p) 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. @@ -1470,7 +1605,7 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags, if (unlikely(!p->numa_group)) { unsigned int size = sizeof(struct numa_group) + - 2*nr_node_ids*sizeof(unsigned long); + 4*nr_node_ids*sizeof(unsigned long); grp = kzalloc(size, GFP_KERNEL | __GFP_NOWARN); if (!grp) @@ -1480,9 +1615,14 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags, 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; - for (i = 0; i < 2*nr_node_ids; i++) - grp->faults[i] = p->numa_faults[i]; + 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; @@ -1539,9 +1679,9 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags, double_lock(&my_grp->lock, &grp->lock); - for (i = 0; i < 2*nr_node_ids; i++) { - my_grp->faults[i] -= p->numa_faults[i]; - grp->faults[i] += p->numa_faults[i]; + 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; @@ -1567,12 +1707,12 @@ void task_numa_free(struct task_struct *p) { struct numa_group *grp = p->numa_group; int i; - void *numa_faults = p->numa_faults; + void *numa_faults = p->numa_faults_memory; if (grp) { spin_lock(&grp->lock); - for (i = 0; i < 2*nr_node_ids; i++) - grp->faults[i] -= p->numa_faults[i]; + 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); @@ -1582,18 +1722,21 @@ void task_numa_free(struct task_struct *p) put_numa_group(grp); } - p->numa_faults = NULL; - p->numa_faults_buffer = NULL; + 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 node, int pages, int flags) +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 priv; if (!numabalancing_enabled) @@ -1608,16 +1751,24 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags) return; /* Allocate buffer to track faults on a per-node basis */ - if (unlikely(!p->numa_faults)) { - int size = sizeof(*p->numa_faults) * 2 * nr_node_ids; + if (unlikely(!p->numa_faults_memory)) { + int size = sizeof(*p->numa_faults_memory) * + NR_NUMA_HINT_FAULT_BUCKETS * nr_node_ids; - /* numa_faults and numa_faults_buffer share the allocation */ - p->numa_faults = kzalloc(size * 2, GFP_KERNEL|__GFP_NOWARN); - if (!p->numa_faults) + p->numa_faults_memory = kzalloc(size, GFP_KERNEL|__GFP_NOWARN); + if (!p->numa_faults_memory) return; - BUG_ON(p->numa_faults_buffer); - p->numa_faults_buffer = p->numa_faults + (2 * nr_node_ids); + 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)); } @@ -1646,7 +1797,8 @@ void task_numa_fault(int last_cpupid, int node, int pages, int flags) if (migrated) p->numa_pages_migrated += pages; - p->numa_faults_buffer[task_faults_idx(node, priv)] += 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[!!(flags & TNF_FAULT_LOCAL)] += pages; } @@ -1762,6 +1914,8 @@ void task_numa_work(struct callback_head *work) start = end; if (pages <= 0) goto out; + + cond_resched(); } while (end != vma->vm_end); } @@ -2222,13 +2376,20 @@ static inline void __update_group_entity_contrib(struct sched_entity *se) se->avg.load_avg_contrib >>= NICE_0_SHIFT; } } -#else + +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) {} -#endif +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) { @@ -2326,12 +2487,6 @@ static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update) __update_cfs_rq_tg_load_contrib(cfs_rq, force_update); } -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); -} - /* 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, @@ -2365,13 +2520,7 @@ static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq, } wakeup = 0; } else { - /* - * Task re-woke on same cpu (or else migrate_task_rq_fair() - * would have made count negative); we must be careful to avoid - * double-accounting blocked time after synchronizing decays. - */ - se->avg.last_runnable_update += __synchronize_entity_decay(se) - << 20; + __synchronize_entity_decay(se); } /* migrated tasks did not contribute to our blocked load */ @@ -2425,7 +2574,10 @@ void idle_exit_fair(struct rq *this_rq) update_rq_runnable_avg(this_rq, 0); } -#else +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) {} @@ -2437,7 +2589,13 @@ static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq, int sleep) {} static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update) {} -#endif + +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) { @@ -2587,10 +2745,10 @@ 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; } } @@ -2598,10 +2756,10 @@ 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; } } @@ -2609,10 +2767,10 @@ 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; } } @@ -2755,17 +2913,36 @@ 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; } @@ -2787,7 +2964,7 @@ 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) { @@ -3442,22 +3619,23 @@ 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 enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer) @@ -3567,7 +3745,7 @@ static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq) } static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, u64 delta_exec) {} -static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} +static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq) { return false; } static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {} static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {} @@ -4101,12 +4279,16 @@ 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; @@ -4218,13 +4400,14 @@ done: } /* - * 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. */ @@ -4274,7 +4457,6 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f } while (sd) { - int load_idx = sd->forkexec_idx; struct sched_group *group; int weight; @@ -4283,10 +4465,7 @@ select_task_rq_fair(struct task_struct *p, int prev_cpu, int sd_flag, int wake_f 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; @@ -4503,26 +4682,124 @@ 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 { - se = pick_next_entity(cfs_rq); + 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, 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; } /* @@ -4760,7 +5037,7 @@ static void move_task(struct task_struct *p, struct lb_env *env) * 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; @@ -4794,7 +5071,7 @@ static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env) { int src_nid, dst_nid; - if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults || + if (!sched_feat(NUMA_FAVOUR_HIGHER) || !p->numa_faults_memory || !(env->sd->flags & SD_NUMA)) { return false; } @@ -4825,7 +5102,7 @@ static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env) if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER)) return false; - if (!p->numa_faults || !(env->sd->flags & SD_NUMA)) + if (!p->numa_faults_memory || !(env->sd->flags & SD_NUMA)) return false; src_nid = cpu_to_node(env->src_cpu); @@ -4921,7 +5198,7 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env) * 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), env->sd); + tsk_cache_hot = task_hot(p, rq_clock_task(env->src_rq)); if (!tsk_cache_hot) tsk_cache_hot = migrate_degrades_locality(p, env); @@ -5512,7 +5789,6 @@ 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 nr_running; unsigned long load; int i; @@ -5521,8 +5797,6 @@ static inline void update_sg_lb_stats(struct lb_env *env, for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { struct rq *rq = cpu_rq(i); - nr_running = rq->nr_running; - /* Bias balancing toward cpus of our domain */ if (local_group) load = target_load(i, load_idx); @@ -5530,7 +5804,7 @@ static inline void update_sg_lb_stats(struct lb_env *env, load = source_load(i, load_idx); sgs->group_load += load; - sgs->sum_nr_running += nr_running; + 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; @@ -5787,12 +6061,10 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) pwr_now /= SCHED_POWER_SCALE; /* Amount of load we'd subtract */ - tmp = (busiest->load_per_task * SCHED_POWER_SCALE) / - busiest->group_power; - if (busiest->avg_load > tmp) { + if (busiest->avg_load > scaled_busy_load_per_task) { pwr_move += busiest->group_power * min(busiest->load_per_task, - busiest->avg_load - tmp); + busiest->avg_load - scaled_busy_load_per_task); } /* Amount of load we'd add */ @@ -6371,17 +6643,23 @@ out: * 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) { struct sched_domain *sd; int pulled_task = 0; unsigned long next_balance = jiffies + HZ; u64 curr_cost = 0; + int this_cpu = this_rq->cpu; + idle_enter_fair(this_rq); + /* + * 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) - return; + goto out; /* * Drop the rq->lock, but keep IRQ/preempt disabled. @@ -6419,15 +6697,22 @@ void idle_balance(int this_cpu, struct rq *this_rq) 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; + if (pulled_task) break; - } |