diff options
| -rw-r--r-- | include/linux/mmzone.h | 6 | ||||
| -rw-r--r-- | include/trace/events/migrate.h | 27 | ||||
| -rw-r--r-- | kernel/sched/core.c | 2 | ||||
| -rw-r--r-- | kernel/sched/deadline.c | 2 | ||||
| -rw-r--r-- | kernel/sched/fair.c | 104 | ||||
| -rw-r--r-- | kernel/sched/sched.h | 3 | ||||
| -rw-r--r-- | mm/migrate.c | 57 | ||||
| -rw-r--r-- | mm/page_alloc.c | 2 |
8 files changed, 95 insertions, 108 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 1e22d96734e0..3f4c0b167333 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -671,12 +671,6 @@ typedef struct pglist_data { #ifdef CONFIG_NUMA_BALANCING /* Lock serializing the migrate rate limiting window */ spinlock_t numabalancing_migrate_lock; - - /* Rate limiting time interval */ - unsigned long numabalancing_migrate_next_window; - - /* Number of pages migrated during the rate limiting time interval */ - unsigned long numabalancing_migrate_nr_pages; #endif /* * This is a per-node reserve of pages that are not available diff --git a/include/trace/events/migrate.h b/include/trace/events/migrate.h index 711372845945..705b33d1e395 100644 --- a/include/trace/events/migrate.h +++ b/include/trace/events/migrate.h @@ -70,33 +70,6 @@ TRACE_EVENT(mm_migrate_pages, __print_symbolic(__entry->mode, MIGRATE_MODE), __print_symbolic(__entry->reason, MIGRATE_REASON)) ); - -TRACE_EVENT(mm_numa_migrate_ratelimit, - - TP_PROTO(struct task_struct *p, int dst_nid, unsigned long nr_pages), - - TP_ARGS(p, dst_nid, nr_pages), - - TP_STRUCT__entry( - __array( char, comm, TASK_COMM_LEN) - __field( pid_t, pid) - __field( int, dst_nid) - __field( unsigned long, nr_pages) - ), - - TP_fast_assign( - memcpy(__entry->comm, p->comm, TASK_COMM_LEN); - __entry->pid = p->pid; - __entry->dst_nid = dst_nid; - __entry->nr_pages = nr_pages; - ), - - TP_printk("comm=%s pid=%d dst_nid=%d nr_pages=%lu", - __entry->comm, - __entry->pid, - __entry->dst_nid, - __entry->nr_pages) -); #endif /* _TRACE_MIGRATE_H */ /* This part must be outside protection */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 625bc9897f62..ad97f3ba5ec5 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1167,7 +1167,7 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu) if (task_cpu(p) != new_cpu) { if (p->sched_class->migrate_task_rq) - p->sched_class->migrate_task_rq(p); + p->sched_class->migrate_task_rq(p, new_cpu); p->se.nr_migrations++; rseq_migrate(p); perf_event_task_migrate(p); diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c index 997ea7b839fa..91e4202b0634 100644 --- a/kernel/sched/deadline.c +++ b/kernel/sched/deadline.c @@ -1607,7 +1607,7 @@ out: return cpu; } -static void migrate_task_rq_dl(struct task_struct *p) +static void migrate_task_rq_dl(struct task_struct *p, int new_cpu __maybe_unused) { struct rq *rq; diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index f808ddf2a868..7fc4a371bdd2 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1392,6 +1392,17 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page, int last_cpupid, this_cpupid; this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid); + last_cpupid = page_cpupid_xchg_last(page, this_cpupid); + + /* + * Allow first faults or private faults to migrate immediately early in + * the lifetime of a task. The magic number 4 is based on waiting for + * two full passes of the "multi-stage node selection" test that is + * executed below. + */ + if ((p->numa_preferred_nid == -1 || p->numa_scan_seq <= 4) && + (cpupid_pid_unset(last_cpupid) || cpupid_match_pid(p, last_cpupid))) + return true; /* * Multi-stage node selection is used in conjunction with a periodic @@ -1410,7 +1421,6 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page, * 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; @@ -1514,6 +1524,21 @@ struct task_numa_env { static void task_numa_assign(struct task_numa_env *env, struct task_struct *p, long imp) { + struct rq *rq = cpu_rq(env->dst_cpu); + + /* Bail out if run-queue part of active NUMA balance. */ + if (xchg(&rq->numa_migrate_on, 1)) + return; + + /* + * Clear previous best_cpu/rq numa-migrate flag, since task now + * found a better CPU to move/swap. + */ + if (env->best_cpu != -1) { + rq = cpu_rq(env->best_cpu); + WRITE_ONCE(rq->numa_migrate_on, 0); + } + if (env->best_task) put_task_struct(env->best_task); if (p) @@ -1553,6 +1578,13 @@ static bool load_too_imbalanced(long src_load, long dst_load, } /* + * Maximum NUMA importance can be 1998 (2*999); + * SMALLIMP @ 30 would be close to 1998/64. + * Used to deter task migration. + */ +#define SMALLIMP 30 + +/* * 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 @@ -1569,6 +1601,9 @@ static void task_numa_compare(struct task_numa_env *env, long moveimp = imp; int dist = env->dist; + if (READ_ONCE(dst_rq->numa_migrate_on)) + return; + rcu_read_lock(); cur = task_rcu_dereference(&dst_rq->curr); if (cur && ((cur->flags & PF_EXITING) || is_idle_task(cur))) @@ -1582,7 +1617,7 @@ static void task_numa_compare(struct task_numa_env *env, goto unlock; if (!cur) { - if (maymove || imp > env->best_imp) + if (maymove && moveimp >= env->best_imp) goto assign; else goto unlock; @@ -1625,16 +1660,22 @@ static void task_numa_compare(struct task_numa_env *env, task_weight(cur, env->dst_nid, dist); } - if (imp <= env->best_imp) - goto unlock; - if (maymove && moveimp > imp && moveimp > env->best_imp) { - imp = moveimp - 1; + imp = moveimp; cur = NULL; goto assign; } /* + * If the NUMA importance is less than SMALLIMP, + * task migration might only result in ping pong + * of tasks and also hurt performance due to cache + * misses. + */ + if (imp < SMALLIMP || imp <= env->best_imp + SMALLIMP / 2) + goto unlock; + + /* * In the overloaded case, try and keep the load balanced. */ load = task_h_load(env->p) - task_h_load(cur); @@ -1710,6 +1751,7 @@ static int task_numa_migrate(struct task_struct *p) .best_cpu = -1, }; struct sched_domain *sd; + struct rq *best_rq; unsigned long taskweight, groupweight; int nid, ret, dist; long taskimp, groupimp; @@ -1805,20 +1847,17 @@ static int task_numa_migrate(struct task_struct *p) if (env.best_cpu == -1) return -EAGAIN; - /* - * 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_start(p); - + best_rq = cpu_rq(env.best_cpu); if (env.best_task == NULL) { ret = migrate_task_to(p, env.best_cpu); + WRITE_ONCE(best_rq->numa_migrate_on, 0); if (ret != 0) trace_sched_stick_numa(p, env.src_cpu, env.best_cpu); return ret; } ret = migrate_swap(p, env.best_task, env.best_cpu, env.src_cpu); + WRITE_ONCE(best_rq->numa_migrate_on, 0); if (ret != 0) trace_sched_stick_numa(p, env.src_cpu, task_cpu(env.best_task)); @@ -2596,6 +2635,39 @@ void task_tick_numa(struct rq *rq, struct task_struct *curr) } } +static void update_scan_period(struct task_struct *p, int new_cpu) +{ + int src_nid = cpu_to_node(task_cpu(p)); + int dst_nid = cpu_to_node(new_cpu); + + if (!static_branch_likely(&sched_numa_balancing)) + return; + + if (!p->mm || !p->numa_faults || (p->flags & PF_EXITING)) + return; + + if (src_nid == dst_nid) + return; + + /* + * Allow resets if faults have been trapped before one scan + * has completed. This is most likely due to a new task that + * is pulled cross-node due to wakeups or load balancing. + */ + if (p->numa_scan_seq) { + /* + * Avoid scan adjustments if moving to the preferred + * node or if the task was not previously running on + * the preferred node. + */ + if (dst_nid == p->numa_preferred_nid || + (p->numa_preferred_nid != -1 && src_nid != p->numa_preferred_nid)) + return; + } + + p->numa_scan_period = task_scan_start(p); +} + #else static void task_tick_numa(struct rq *rq, struct task_struct *curr) { @@ -2609,6 +2681,10 @@ static inline void account_numa_dequeue(struct rq *rq, struct task_struct *p) { } +static inline void update_scan_period(struct task_struct *p, int new_cpu) +{ +} + #endif /* CONFIG_NUMA_BALANCING */ static void @@ -6275,7 +6351,7 @@ static void detach_entity_cfs_rq(struct sched_entity *se); * cfs_rq_of(p) references at time of call are still valid and identify the * previous CPU. The caller guarantees p->pi_lock or task_rq(p)->lock is held. */ -static void migrate_task_rq_fair(struct task_struct *p) +static void migrate_task_rq_fair(struct task_struct *p, int new_cpu) { /* * As blocked tasks retain absolute vruntime the migration needs to @@ -6328,6 +6404,8 @@ static void migrate_task_rq_fair(struct task_struct *p) /* We have migrated, no longer consider this task hot */ p->se.exec_start = 0; + + update_scan_period(p, new_cpu); } static void task_dead_fair(struct task_struct *p) diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4a2e8cae63c4..455fa330de04 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -783,6 +783,7 @@ struct rq { #ifdef CONFIG_NUMA_BALANCING unsigned int nr_numa_running; unsigned int nr_preferred_running; + unsigned int numa_migrate_on; #endif #define CPU_LOAD_IDX_MAX 5 unsigned long cpu_load[CPU_LOAD_IDX_MAX]; @@ -1523,7 +1524,7 @@ struct sched_class { #ifdef CONFIG_SMP int (*select_task_rq)(struct task_struct *p, int task_cpu, int sd_flag, int flags); - void (*migrate_task_rq)(struct task_struct *p); + void (*migrate_task_rq)(struct task_struct *p, int new_cpu); void (*task_woken)(struct rq *this_rq, struct task_struct *task); diff --git a/mm/migrate.c b/mm/migrate.c index d6a2e89b086a..5e285c1249a0 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1855,46 +1855,6 @@ static struct page *alloc_misplaced_dst_page(struct page *page, return newpage; } -/* - * page migration rate limiting control. - * Do not migrate more than @pages_to_migrate in a @migrate_interval_millisecs - * window of time. Default here says do not migrate more than 1280M per second. - */ -static unsigned int migrate_interval_millisecs __read_mostly = 100; -static unsigned int ratelimit_pages __read_mostly = 128 << (20 - PAGE_SHIFT); - -/* Returns true if the node is migrate rate-limited after the update */ -static bool numamigrate_update_ratelimit(pg_data_t *pgdat, - unsigned long nr_pages) -{ - /* - * Rate-limit the amount of data that is being migrated to a node. - * Optimal placement is no good if the memory bus is saturated and - * all the time is being spent migrating! - */ - if (time_after(jiffies, pgdat->numabalancing_migrate_next_window)) { - spin_lock(&pgdat->numabalancing_migrate_lock); - pgdat->numabalancing_migrate_nr_pages = 0; - pgdat->numabalancing_migrate_next_window = jiffies + - msecs_to_jiffies(migrate_interval_millisecs); - spin_unlock(&pgdat->numabalancing_migrate_lock); - } - if (pgdat->numabalancing_migrate_nr_pages > ratelimit_pages) { - trace_mm_numa_migrate_ratelimit(current, pgdat->node_id, - nr_pages); - return true; - } - - /* - * This is an unlocked non-atomic update so errors are possible. - * The consequences are failing to migrate when we potentiall should - * have which is not severe enough to warrant locking. If it is ever - * a problem, it can be converted to a per-cpu counter. - */ - pgdat->numabalancing_migrate_nr_pages += nr_pages; - return false; -} - static int numamigrate_isolate_page(pg_data_t *pgdat, struct page *page) { int page_lru; @@ -1967,14 +1927,6 @@ int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma, if (page_is_file_cache(page) && PageDirty(page)) goto out; - /* - * Rate-limit the amount of data that is being migrated to a node. - * Optimal placement is no good if the memory bus is saturated and - * all the time is being spent migrating! - */ - if (numamigrate_update_ratelimit(pgdat, 1)) - goto out; - isolated = numamigrate_isolate_page(pgdat, page); if (!isolated) goto out; @@ -2021,14 +1973,6 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm, unsigned long mmun_start = address & HPAGE_PMD_MASK; unsigned long mmun_end = mmun_start + HPAGE_PMD_SIZE; - /* - * Rate-limit the amount of data that is being migrated to a node. - * Optimal placement is no good if the memory bus is saturated and - * all the time is being spent migrating! - */ - if (numamigrate_update_ratelimit(pgdat, HPAGE_PMD_NR)) - goto out_dropref; - new_page = alloc_pages_node(node, (GFP_TRANSHUGE_LIGHT | __GFP_THISNODE), HPAGE_PMD_ORDER); @@ -2125,7 +2069,6 @@ int migrate_misplaced_transhuge_page(struct mm_struct *mm, out_fail: count_vm_events(PGMIGRATE_FAIL, HPAGE_PMD_NR); -out_dropref: ptl = pmd_lock(mm, pmd); if (pmd_same(*pmd, entry)) { entry = pmd_modify(entry, vma->vm_page_prot); diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 89d2a2ab3fe6..706a738c0aee 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -6197,8 +6197,6 @@ static unsigned long __init calc_memmap_size(unsigned long spanned_pages, static void pgdat_init_numabalancing(struct pglist_data *pgdat) { spin_lock_init(&pgdat->numabalancing_migrate_lock); - pgdat->numabalancing_migrate_nr_pages = 0; - pgdat->numabalancing_migrate_next_window = jiffies; } #else static void pgdat_init_numabalancing(struct pglist_data *pgdat) {} |