Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752231Ab3IJJd5 (ORCPT ); Tue, 10 Sep 2013 05:33:57 -0400 Received: from cantor2.suse.de ([195.135.220.15]:57364 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750963Ab3IJJd0 (ORCPT ); Tue, 10 Sep 2013 05:33:26 -0400 From: Mel Gorman To: Peter Zijlstra , Rik van Riel Cc: Srikar Dronamraju , Ingo Molnar , Andrea Arcangeli , Johannes Weiner , Linux-MM , LKML , Mel Gorman Subject: [PATCH 50/50] sched: numa: Avoid migrating tasks that are placed on their preferred node Date: Tue, 10 Sep 2013 10:32:30 +0100 Message-Id: <1378805550-29949-51-git-send-email-mgorman@suse.de> X-Mailer: git-send-email 1.8.1.4 In-Reply-To: <1378805550-29949-1-git-send-email-mgorman@suse.de> References: <1378805550-29949-1-git-send-email-mgorman@suse.de> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10371 Lines: 342 From: Peter Zijlstra (This changelog needs more work, it's currently inaccurate and it's not clear at exactly what point rt > env->fbq_type is true for the logic to kick in) This patch classifies scheduler domains and runqueues into FBQ (cannot guess what this expands to) types which are one of regular: There are tasks running that do not care about their NUMA placement remote: There are tasks running that care about their placement but are currently running on a node remote to their ideal placement all: No distinction To implement this the patch tracks the number of tasks that are optimally NUMA placed (rq->nr_preferred_running) and the number of tasks running that care about their placement (nr_numa_running). The load balancer uses this information to avoid migrating idea placed NUMA tasks as long as better options for load balancing exists. Not-signed-off-by: Peter Zijlstra --- kernel/sched/core.c | 29 ++++++++++++ kernel/sched/fair.c | 128 ++++++++++++++++++++++++++++++++++++++++++++++----- kernel/sched/sched.h | 5 ++ 3 files changed, 150 insertions(+), 12 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 7bf0827..3fc31b7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -4485,6 +4485,35 @@ int migrate_task_to(struct task_struct *p, int target_cpu) return stop_one_cpu(curr_cpu, migration_cpu_stop, &arg); } + +/* + * Requeue a task on a given node and accurately track the number of NUMA + * tasks on the runqueues + */ +void sched_setnuma(struct task_struct *p, int nid) +{ + struct rq *rq; + unsigned long flags; + bool on_rq, running; + + rq = task_rq_lock(p, &flags); + on_rq = p->on_rq; + running = task_current(rq, p); + + if (on_rq) + dequeue_task(rq, p, 0); + if (running) + p->sched_class->put_prev_task(rq, p); + + p->numa_preferred_nid = nid; + p->numa_migrate_seq = 1; + + if (running) + p->sched_class->set_curr_task(rq); + if (on_rq) + enqueue_task(rq, p, 0); + task_rq_unlock(rq, p, &flags); +} #endif /* diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index ac7184d..27bc89b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -888,6 +888,18 @@ static unsigned int task_scan_max(struct task_struct *p) */ 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; @@ -1229,6 +1241,8 @@ static int task_numa_migrate(struct task_struct *p) if (env.best_cpu == -1) return -EAGAIN; + sched_setnuma(p, env.dst_nid); + if (env.best_task == NULL) { int ret = migrate_task_to(p, env.best_cpu); return ret; @@ -1340,8 +1354,7 @@ static void task_numa_placement(struct task_struct *p) /* 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 */ - p->numa_preferred_nid = max_nid; - p->numa_migrate_seq = 1; + sched_setnuma(p, max_nid); numa_migrate_preferred(p); } } @@ -1736,6 +1749,14 @@ 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 @@ -1745,8 +1766,12 @@ 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++; } @@ -1757,8 +1782,10 @@ 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--; } @@ -4553,6 +4580,8 @@ static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preemp 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 @@ -4579,6 +4608,8 @@ struct lb_env { unsigned int loop; unsigned int loop_break; unsigned int loop_max; + + enum fbq_type fbq_type; }; /* @@ -5044,6 +5075,10 @@ struct sg_lb_stats { 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? */ +#ifdef CONFIG_NUMA_BALANCING + unsigned int nr_numa_running; + unsigned int nr_preferred_running; +#endif }; /* @@ -5335,6 +5370,10 @@ static inline void update_sg_lb_stats(struct lb_env *env, sgs->group_load += load; sgs->sum_nr_running += 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++; @@ -5409,14 +5448,43 @@ static bool update_sd_pick_busiest(struct lb_env *env, 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. * @env: The load balancing environment. * @balance: Should we balance. * @sds: variable to hold the statistics for this sched_domain. */ -static inline void update_sd_lb_stats(struct lb_env *env, - 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 = env->sd->child; struct sched_group *sg = env->sd->groups; @@ -5466,6 +5534,9 @@ static inline void update_sd_lb_stats(struct lb_env *env, sg = sg->next; } while (sg != env->sd->groups); + + if (env->sd->flags & SD_NUMA) + env->fbq_type = fbq_classify_group(&sds->busiest_stat); } /** @@ -5768,15 +5839,47 @@ static struct rq *find_busiest_queue(struct lb_env *env, int i; for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { - unsigned long power = power_of(i); - unsigned long capacity = DIV_ROUND_CLOSEST(power, - SCHED_POWER_SCALE); - unsigned long wl; + unsigned long power, capacity, wl; + enum fbq_type rt; + rq = cpu_rq(i); + rt = fbq_classify_rq(rq); + +#ifdef CONFIG_NUMA_BALANCING + trace_printk("group(%d:%pc) rq(%d): wl: %lu nr: %d nrn: %d nrp: %d gt:%d rt:%d\n", + env->sd->level, sched_group_cpus(group), i, + weighted_cpuload(i), rq->nr_running, + rq->nr_numa_running, rq->nr_preferred_running, + env->fbq_type, rt); +#endif + + /* + * 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; + + power = power_of(i); + capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE); if (!capacity) capacity = fix_small_capacity(env->sd, group); - rq = cpu_rq(i); wl = weighted_cpuload(i); /* @@ -5888,6 +5991,7 @@ static int load_balance(int this_cpu, struct rq *this_rq, .idle = idle, .loop_break = sched_nr_migrate_break, .cpus = cpus, + .fbq_type = all, }; /* diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4c6ec25..b9bcea5 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -407,6 +407,10 @@ struct rq { * remote CPUs use both these fields when doing load calculation. */ unsigned int nr_running; +#ifdef CONFIG_NUMA_BALANCING + unsigned int nr_numa_running; + unsigned int nr_preferred_running; +#endif #define CPU_LOAD_IDX_MAX 5 unsigned long cpu_load[CPU_LOAD_IDX_MAX]; unsigned long last_load_update_tick; @@ -555,6 +559,7 @@ static inline u64 rq_clock_task(struct rq *rq) } #ifdef CONFIG_NUMA_BALANCING +extern void sched_setnuma(struct task_struct *p, int node); extern int migrate_task_to(struct task_struct *p, int cpu); extern int migrate_swap(struct task_struct *, struct task_struct *); extern void task_numa_free(struct task_struct *p); -- 1.8.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/