diff options
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 1397 |
1 files changed, 1193 insertions, 204 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7c70201fbc6..df77c605c7a 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -681,6 +681,8 @@ static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se) } #ifdef CONFIG_SMP +static unsigned long task_h_load(struct task_struct *p); + static inline void __update_task_entity_contrib(struct sched_entity *se); /* Give new task start runnable values to heavy its load in infant time */ @@ -818,11 +820,12 @@ update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se) #ifdef CONFIG_NUMA_BALANCING /* - * numa task sample period in ms + * 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 = 100; -unsigned int sysctl_numa_balancing_scan_period_max = 100*50; -unsigned int sysctl_numa_balancing_scan_period_reset = 100*600; +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; @@ -830,41 +833,810 @@ 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 void task_numa_placement(struct task_struct *p) +/* + * 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; + 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; +} + +/* 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); +} + +static unsigned int task_scan_max(struct task_struct *p) +{ + 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); +} + +/* + * 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); + 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; + unsigned long total_faults; + unsigned long faults[0]; +}; + +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 2 * nid + priv; +} + +static inline unsigned long task_faults(struct task_struct *p, int nid) +{ + if (!p->numa_faults) + return 0; + + return p->numa_faults[task_faults_idx(nid, 0)] + + p->numa_faults[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[2*nid] + p->numa_group->faults[2*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) + 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) { - int seq; + if (!p->numa_group || !p->numa_group->total_faults) + return 0; - if (!p->mm) /* for example, ksmd faulting in a user's mm */ + return 1000 * group_faults(p, nid) / p->numa_group->total_faults; +} + +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 power_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 power; + + /* Approximate capacity in terms of runnable tasks on a node */ + unsigned long capacity; + int has_capacity; +}; + +/* + * XXX borrowed from update_sg_lb_stats + */ +static void update_numa_stats(struct numa_stats *ns, int nid) +{ + int cpu; + + 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->power += power_of(cpu); + } + + ns->load = (ns->load * SCHED_POWER_SCALE) / ns->power; + ns->capacity = DIV_ROUND_CLOSEST(ns->power, SCHED_POWER_SCALE); + ns->has_capacity = (ns->nr_running < ns->capacity); +} + +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, idx; + + 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) +{ + 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; +} + +/* + * 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 dst_load, src_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); + } + } + + if (imp < env->best_imp) + goto unlock; + + if (!cur) { + /* Is there capacity at our destination? */ + if (env->src_stats.has_capacity && + !env->dst_stats.has_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: + dst_load = env->dst_stats.load; + src_load = env->src_stats.load; + + /* XXX missing power terms */ + load = task_h_load(env->p); + dst_load += load; + src_load -= load; + + if (cur) { + load = task_h_load(cur); + dst_load -= load; + src_load += load; + } + + /* make src_load the smaller */ + if (dst_load < src_load) + swap(dst_load, src_load); + + if (src_load * env->imbalance_pct < dst_load * 100) + goto unlock; + +assign: + task_numa_assign(env, cur, imp); +unlock: + rcu_read_unlock(); +} + +static void task_numa_find_cpu(struct task_numa_env *env, + long taskimp, long groupimp) +{ + 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)); + env.imbalance_pct = 100 + (sd->imbalance_pct - 100) / 2; + rcu_read_unlock(); + + 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 capacity, try to use it. */ + if (env.dst_stats.has_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; + + 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) { + int ret = migrate_task_to(p, env.best_cpu); + return ret; + } + + ret = migrate_swap(p, 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) +{ + /* This task has no NUMA fault statistics yet */ + if (unlikely(p->numa_preferred_nid == -1 || !p->numa_faults)) + 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) return; + + /* Otherwise, try migrate to a CPU on the preferred node */ + task_numa_migrate(p); +} + +/* + * 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 + */ + 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; + } + + 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)); +} + +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 }; + 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); + + /* 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(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 < 2; priv++) { + long diff; + + 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; + + faults += p->numa_faults[i]; + diff += p->numa_faults[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->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) { + /* + * 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(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) + + 2*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; + + for (i = 0; i < 2*nr_node_ids; i++) + grp->faults[i] = p->numa_faults[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); + } + + 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; - /* FIXME: Scheduling placement policy hints go here */ + rcu_read_unlock(); + + if (!join) + return; + + 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]; + } + 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(&grp->lock); + + rcu_assign_pointer(p->numa_group, grp); + + put_numa_group(my_grp); + return; + +no_join: + rcu_read_unlock(); + return; +} + +void task_numa_free(struct task_struct *p) +{ + struct numa_group *grp = p->numa_group; + int i; + void *numa_faults = p->numa_faults; + + if (grp) { + spin_lock(&grp->lock); + for (i = 0; i < 2*nr_node_ids; i++) + grp->faults[i] -= p->numa_faults[i]; + grp->total_faults -= p->total_numa_faults; + + list_del(&p->numa_entry); + grp->nr_tasks--; + spin_unlock(&grp->lock); + rcu_assign_pointer(p->numa_group, NULL); + put_numa_group(grp); + } + + p->numa_faults = NULL; + p->numa_faults_buffer = NULL; + kfree(numa_faults); } /* * Got a PROT_NONE fault for a page on @node. */ -void task_numa_fault(int node, int pages, bool migrated) +void task_numa_fault(int last_cpupid, int node, int pages, int flags) { struct task_struct *p = current; + bool migrated = flags & TNF_MIGRATED; + int priv; if (!numabalancing_enabled) return; - /* FIXME: Allocate task-specific structure for placement policy here */ + /* for example, ksmd faulting in a user's mm */ + if (!p->mm) + return; + + /* Do not worry about placement if exiting */ + if (p->state == TASK_DEAD) + 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; + + /* numa_faults and numa_faults_buffer share the allocation */ + p->numa_faults = kzalloc(size * 2, GFP_KERNEL|__GFP_NOWARN); + if (!p->numa_faults) + return; + + BUG_ON(p->numa_faults_buffer); + p->numa_faults_buffer = p->numa_faults + (2 * nr_node_ids); + p->total_numa_faults = 0; + memset(p->numa_faults_locality, 0, sizeof(p->numa_faults_locality)); + } /* - * If pages are properly placed (did not migrate) then scan slower. - * This is reset periodically in case of phase changes + * First accesses are treated as private, otherwise consider accesses + * to be private if the accessing pid has not changed */ - if (!migrated) - p->numa_scan_period = min(sysctl_numa_balancing_scan_period_max, - p->numa_scan_period + jiffies_to_msecs(10)); + 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); + } 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[task_faults_idx(node, priv)] += pages; + p->numa_faults_locality[!!(flags & TNF_FAULT_LOCAL)] += pages; } static void reset_ptenuma_scan(struct task_struct *p) @@ -884,6 +1656,7 @@ void task_numa_work(struct callback_head *work) 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)); @@ -900,35 +1673,9 @@ void task_numa_work(struct callback_head *work) if (p->flags & PF_EXITING) return; - /* - * We do not care about task placement until a task runs on a node - * other than the first one used by the address space. This is - * largely because migrations are driven by what CPU the task - * is running on. If it's never scheduled on another node, it'll - * not migrate so why bother trapping the fault. - */ - if (mm->first_nid == NUMA_PTE_SCAN_INIT) - mm->first_nid = numa_node_id(); - if (mm->first_nid != NUMA_PTE_SCAN_ACTIVE) { - /* Are we running on a new node yet? */ - if (numa_node_id() == mm->first_nid && - !sched_feat_numa(NUMA_FORCE)) - return; - - mm->first_nid = NUMA_PTE_SCAN_ACTIVE; - } - - /* - * Reset the scan period if enough time has gone by. Objective is that - * scanning will be reduced if pages are properly placed. As tasks - * can enter different phases this needs to be re-examined. Lacking - * proper tracking of reference behaviour, this blunt hammer is used. - */ - migrate = mm->numa_next_reset; - if (time_after(now, migrate)) { - p->numa_scan_period = sysctl_numa_balancing_scan_period_min; - next_scan = now + msecs_to_jiffies(sysctl_numa_balancing_scan_period_reset); - xchg(&mm->numa_next_reset, next_scan); + if (!mm->numa_next_scan) { + mm->numa_next_scan = now + + msecs_to_jiffies(sysctl_numa_balancing_scan_delay); } /* @@ -938,20 +1685,20 @@ void task_numa_work(struct callback_head *work) if (time_before(now, migrate)) return; - if (p->numa_scan_period == 0) - p->numa_scan_period = sysctl_numa_balancing_scan_period_min; + 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; /* - * Do not set pte_numa if the current running node is rate-limited. - * This loses statistics on the fault but if we are unwilling to - * migrate to this node, it is less likely we can do useful work + * Delay this task enough that another task of this mm will likely win + * the next time around. */ - if (migrate_ratelimited(numa_node_id())) - return; + p->node_stamp += 2 * TICK_NSEC; start = mm->numa_scan_offset; pages = sysctl_numa_balancing_scan_size; @@ -967,18 +1714,32 @@ void task_numa_work(struct callback_head *work) vma = mm->mmap; } for (; vma; vma = vma->vm_next) { - if (!vma_migratable(vma)) + if (!vma_migratable(vma) || !vma_policy_mof(p, vma)) continue; - /* Skip small VMAs. They are not likely to be of relevance */ - if (vma->vm_end - vma->vm_start < HPAGE_SIZE) + /* + * 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; do { start = max(start, vma->vm_start); end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE); end = min(end, vma->vm_end); - pages -= change_prot_numa(vma, start, 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) @@ -988,10 +1749,10 @@ void task_numa_work(struct callback_head *work) 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. + * 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; @@ -1025,8 +1786,8 @@ void task_tick_numa(struct rq *rq, struct task_struct *curr) if (now - curr->node_stamp > period) { if (!curr->node_stamp) - curr->numa_scan_period = sysctl_numa_balancing_scan_period_min; - curr->node_stamp = now; + 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() */ @@ -1038,6 +1799,14 @@ void task_tick_numa(struct rq *rq, struct task_struct *curr) static void task_tick_numa(struct rq *rq, struct task_struct *curr) { } + +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 @@ -1047,8 +1816,12 @@ account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se) if (!parent_entity(se)) update_load_add(&rq_of(cfs_rq)->load, se->load.weight); #ifdef CONFIG_SMP - if (entity_is_task(se)) - list_add(&se->group_node, &rq_of(cfs_rq)->cfs_tasks); + 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++; } @@ -1059,8 +1832,10 @@ 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)) + 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--; } @@ -2070,13 +2845,14 @@ static inline bool cfs_bandwidth_used(void) return static_key_false(&__cfs_bandwidth_used); } -void account_cfs_bandwidth_used(int enabled, int was_enabled) +void cfs_bandwidth_usage_inc(void) +{ + static_key_slow_inc(&__cfs_bandwidth_used); +} + +void cfs_bandwidth_usage_dec(void) { - /* only need to count groups transitioning between enabled/!enabled */ - if (enabled && !was_enabled) - static_key_slow_inc(&__cfs_bandwidth_used); - else if (!enabled && was_enabled) - static_key_slow_dec(&__cfs_bandwidth_used); + static_key_slow_dec(&__cfs_bandwidth_used); } #else /* HAVE_JUMP_LABEL */ static bool cfs_bandwidth_used(void) @@ -2084,7 +2860,8 @@ 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 */ /* @@ -2335,6 +3112,8 @@ static void throttle_cfs_rq(struct cfs_rq *cfs_rq) 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); raw_spin_unlock(&cfs_b->lock); } @@ -2448,6 +3227,13 @@ static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun) if (idle) goto out_unlock; + /* + * 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) { @@ -2508,7 +3294,13 @@ 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; @@ -2584,10 +3376,12 @@ 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; @@ -2708,11 +3502,11 @@ 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_ca |