diff options
| -rw-r--r-- | kernel/sched/fair.c | 87 |
1 files changed, 47 insertions, 40 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 51a4550..7ce24a4 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -932,10 +932,11 @@ struct numa_group { spinlock_t lock; /* nr_tasks, tasks */ int nr_tasks; pid_t gid; + int active_nodes; struct rcu_head rcu; - nodemask_t active_nodes; unsigned long total_faults; + unsigned long max_faults_cpu; /* * Faults_cpu is used to decide whether memory should move * towards the CPU. As a consequence, these stats are weighted @@ -994,6 +995,18 @@ static inline unsigned long group_faults_cpu(struct numa_group *group, int nid) group->faults_cpu[task_faults_idx(NUMA_MEM, nid, 1)]; } +/* + * A node triggering more than 1/3 as many NUMA faults as the maximum is + * considered part of a numa group's pseudo-interleaving set. Migrations + * between these nodes are slowed down, to allow things to settle down. + */ +#define ACTIVE_NODE_FRACTION 3 + +static bool numa_is_active_node(int nid, struct numa_group *ng) +{ + return group_faults_cpu(ng, nid) * ACTIVE_NODE_FRACTION > ng->max_faults_cpu; +} + /* Handle placement on systems where not all nodes are directly connected. */ static unsigned long score_nearby_nodes(struct task_struct *p, int nid, int maxdist, bool task) @@ -1143,27 +1156,23 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page, return true; /* - * Do not migrate if the destination is not a node that - * is actively used by this numa group. + * Destination node is much more heavily used than the source + * node? Allow migration. */ - 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)) + if (group_faults_cpu(ng, dst_nid) > group_faults_cpu(ng, src_nid) * + ACTIVE_NODE_FRACTION) 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. + * Distribute memory according to CPU & memory use on each node, + * with 3/4 hysteresis to avoid unnecessary memory migrations: + * + * faults_cpu(dst) 3 faults_cpu(src) + * --------------- * - > --------------- + * faults_mem(dst) 4 faults_mem(src) */ - return group_faults(p, dst_nid) < (group_faults(p, src_nid) * 3 / 4); + return group_faults_cpu(ng, dst_nid) * group_faults(p, src_nid) * 3 > + group_faults_cpu(ng, src_nid) * group_faults(p, dst_nid) * 4; } static unsigned long weighted_cpuload(const int cpu); @@ -1509,7 +1518,7 @@ static int task_numa_migrate(struct task_struct *p) .best_task = NULL, .best_imp = 0, - .best_cpu = -1 + .best_cpu = -1, }; struct sched_domain *sd; unsigned long taskweight, groupweight; @@ -1561,8 +1570,7 @@ static int task_numa_migrate(struct task_struct *p) * multiple NUMA nodes; in order to better consolidate the group, * we need to check other locations. */ - if (env.best_cpu == -1 || (p->numa_group && - nodes_weight(p->numa_group->active_nodes) > 1)) { + if (env.best_cpu == -1 || (p->numa_group && p->numa_group->active_nodes > 1)) { for_each_online_node(nid) { if (nid == env.src_nid || nid == p->numa_preferred_nid) continue; @@ -1597,12 +1605,14 @@ static int task_numa_migrate(struct task_struct *p) * trying for a better one later. Do not set the preferred node here. */ if (p->numa_group) { + struct numa_group *ng = p->numa_group; + if (env.best_cpu == -1) nid = env.src_nid; else nid = env.dst_nid; - if (node_isset(nid, p->numa_group->active_nodes)) + if (ng->active_nodes > 1 && numa_is_active_node(env.dst_nid, ng)) sched_setnuma(p, env.dst_nid); } @@ -1652,20 +1662,15 @@ static void numa_migrate_preferred(struct task_struct *p) } /* - * Find the nodes on which the workload is actively running. We do this by + * Find out how many nodes on the workload is actively running on. 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) +static void numa_group_count_active_nodes(struct numa_group *numa_group) { unsigned long faults, max_faults = 0; - int nid; + int nid, active_nodes = 0; for_each_online_node(nid) { faults = group_faults_cpu(numa_group, nid); @@ -1675,12 +1680,12 @@ static void update_numa_active_node_mask(struct numa_group *numa_group) 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); + if (faults * ACTIVE_NODE_FRACTION > max_faults) + active_nodes++; } + + numa_group->max_faults_cpu = max_faults; + numa_group->active_nodes = active_nodes; } /* @@ -1971,7 +1976,7 @@ 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); + numa_group_count_active_nodes(p->numa_group); spin_unlock_irq(group_lock); max_nid = preferred_group_nid(p, max_group_nid); } @@ -2015,14 +2020,14 @@ static void task_numa_group(struct task_struct *p, int cpupid, int flags, return; atomic_set(&grp->refcount, 1); + grp->active_nodes = 1; + grp->max_faults_cpu = 0; spin_lock_init(&grp->lock); 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[i]; @@ -2136,6 +2141,7 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) bool migrated = flags & TNF_MIGRATED; int cpu_node = task_node(current); int local = !!(flags & TNF_FAULT_LOCAL); + struct numa_group *ng; int priv; if (!static_branch_likely(&sched_numa_balancing)) @@ -2176,9 +2182,10 @@ void task_numa_fault(int last_cpupid, int mem_node, int pages, int flags) * 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)) + ng = p->numa_group; + if (!priv && !local && ng && ng->active_nodes > 1 && + numa_is_active_node(cpu_node, ng) && + numa_is_active_node(mem_node, ng)) local = 1; task_numa_placement(p); |