There were a few inconsistencies in how numa_allow_migration() was
used, in particular it did no always take into account
high-imbalance scenarios, where affinity preferences are generally
overriden.
To fix this make use of numa_allow_migration() more consistent and
also pass in the load-balancing environment to the function, where
it can look at env->failed and env->sd->cache_nice_tries.
Also add a NUMA check to ALB.
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijls...@chello.nl>
Cc: Andrea Arcangeli <aarca...@redhat.com>
Cc: Rik van Riel <r...@redhat.com>
Cc: Mel Gorman <mgor...@suse.de>
Cc: Hugh Dickins <hu...@google.com>
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
kernel/sched/fair.c | 103 +++++++++++++++++++++++++++++-----------------------
1 file changed, 57 insertions(+), 46 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index c393fba..503ec29 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4792,6 +4792,39 @@ static inline unsigned long effective_load(struct
task_group *tg, int cpu,
#endif
+#define LBF_ALL_PINNED 0x01
+#define LBF_NEED_BREAK 0x02
+#define LBF_SOME_PINNED 0x04
+
+struct lb_env {
+ struct sched_domain *sd;
+
+ struct rq *src_rq;
+ int src_cpu;
+
+ int dst_cpu;
+ struct rq *dst_rq;
+
+ struct cpumask *dst_grpmask;
+ int new_dst_cpu;
+ enum cpu_idle_type idle;
+ long imbalance;
+ /* The set of CPUs under consideration for load-balancing */
+ struct cpumask *cpus;
+
+ unsigned int flags;
+ unsigned int failed;
+ unsigned int iteration;
+
+ unsigned int loop;
+ unsigned int loop_break;
+ unsigned int loop_max;
+
+ struct rq * (*find_busiest_queue)(struct lb_env *,
+ struct sched_group *);
+};
+
+
static int wake_affine(struct sched_domain *sd, struct task_struct *p, int
sync)
{
s64 this_load, load;
@@ -5011,30 +5044,35 @@ done:
return target;
}
-static bool numa_allow_migration(struct task_struct *p, int prev_cpu, int
new_cpu)
+static bool numa_allow_migration(struct task_struct *p, int prev_cpu, int
new_cpu,
+ struct lb_env *env)
{
#ifdef CONFIG_NUMA_BALANCING
+
if (sched_feat(NUMA_CONVERGE_MIGRATIONS)) {
/* Help in the direction of expected convergence: */
if (p->convergence_node >= 0 && (cpu_to_node(new_cpu) !=
p->convergence_node))
return false;
- return true;
- }
-
- if (sched_feat(NUMA_BALANCE_ALL)) {
- if (task_numa_shared(p) >= 0)
- return false;
-
- return true;
+ if (!env || env->failed <= env->sd->cache_nice_tries) {
+ if (task_numa_shared(p) >= 0 &&
+ cpu_to_node(prev_cpu) !=
cpu_to_node(new_cpu))
+ return false;
+ }
}
if (sched_feat(NUMA_BALANCE_INTERNODE)) {
if (task_numa_shared(p) >= 0) {
- if (cpu_to_node(prev_cpu) != cpu_to_node(new_cpu))
+ if (cpu_to_node(prev_cpu) != cpu_to_node(new_cpu))
return false;
}
}
+
+ if (sched_feat(NUMA_BALANCE_ALL)) {
+ if (task_numa_shared(p) >= 0)
+ return false;
+ }
+
#endif
return true;
}
@@ -5148,7 +5186,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag,
int wake_flags)
/* while loop will break here if sd == NULL */
}
unlock:
- if (!numa_allow_migration(p, prev0_cpu, new_cpu)) {
+ if (!numa_allow_migration(p, prev0_cpu, new_cpu, NULL)) {
if (cpumask_test_cpu(prev0_cpu, tsk_cpus_allowed(p)))
new_cpu = prev0_cpu;
}
@@ -5567,38 +5605,6 @@ 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;
-#define LBF_ALL_PINNED 0x01
-#define LBF_NEED_BREAK 0x02
-#define LBF_SOME_PINNED 0x04
-
-struct lb_env {
- struct sched_domain *sd;
-
- struct rq *src_rq;
- int src_cpu;
-
- int dst_cpu;
- struct rq *dst_rq;
-
- struct cpumask *dst_grpmask;
- int new_dst_cpu;
- enum cpu_idle_type idle;
- long imbalance;
- /* The set of CPUs under consideration for load-balancing */
- struct cpumask *cpus;
-
- unsigned int flags;
- unsigned int failed;
- unsigned int iteration;
-
- unsigned int loop;
- unsigned int loop_break;
- unsigned int loop_max;
-
- struct rq * (*find_busiest_queue)(struct lb_env *,
- struct sched_group *);
-};
-
/*
* move_task - move a task from one runqueue to another runqueue.
* Both runqueues must be locked.
@@ -5699,7 +5705,7 @@ static int can_migrate_task(struct task_struct *p, struct
lb_env *env)
/* We do NUMA balancing elsewhere: */
if (env->failed <= env->sd->cache_nice_tries) {
- if (!numa_allow_migration(p, env->src_rq->cpu, env->dst_cpu))
+ if (!numa_allow_migration(p, env->src_rq->cpu, env->dst_cpu,
env))
return false;
}
@@ -5760,7 +5766,7 @@ static int move_one_task(struct lb_env *env)
if (!can_migrate_task(p, env))
continue;
- if (!numa_allow_migration(p, env->src_rq->cpu, env->dst_cpu))
+ if (!numa_allow_migration(p, env->src_rq->cpu, env->dst_cpu,
env))
continue;
move_task(p, env);
@@ -5823,7 +5829,7 @@ static int move_tasks(struct lb_env *env)
if (!can_migrate_task(p, env))
goto next;
- if (!numa_allow_migration(p, env->src_rq->cpu, env->dst_cpu))
+ if (!numa_allow_migration(p, env->src_rq->cpu, env->dst_cpu,
env))
goto next;
move_task(p, env);
@@ -6944,6 +6950,11 @@ more_balance:
goto out_pinned;
}
+ /* Is this active load-balancing NUMA-beneficial? */
+ if (!numa_allow_migration(busiest->curr, env.src_rq->cpu,
env.dst_cpu, &env)) {
+ raw_spin_unlock_irqrestore(&busiest->lock, flags);
+ goto out;
+ }
/*
* ->active_balance synchronizes accesses to
* ->active_balance_work. Once set, it's cleared
--
1.7.11.7
--
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