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-rw-r--r--kernel/sched/fair.c33
-rw-r--r--kernel/sched/features.h8
2 files changed, 41 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6ffddca687fe..89431248d33d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4107,12 +4107,43 @@ static bool migrate_improves_locality(struct task_struct *p, struct lb_env *env)
return false;
}
+
+
+static bool migrate_degrades_locality(struct task_struct *p, struct lb_env *env)
+{
+ int src_nid, dst_nid;
+
+ if (!sched_feat(NUMA) || !sched_feat(NUMA_RESIST_LOWER))
+ return false;
+
+ if (!p->numa_faults || !(env->sd->flags & SD_NUMA))
+ return false;
+
+ src_nid = cpu_to_node(env->src_cpu);
+ dst_nid = cpu_to_node(env->dst_cpu);
+
+ if (src_nid == dst_nid ||
+ p->numa_migrate_seq >= sysctl_numa_balancing_settle_count)
+ return false;
+
+ if (p->numa_faults[dst_nid] < p->numa_faults[src_nid])
+ return true;
+
+ return false;
+}
+
#else
static inline bool migrate_improves_locality(struct task_struct *p,
struct lb_env *env)
{
return false;
}
+
+static inline bool migrate_degrades_locality(struct task_struct *p,
+ struct lb_env *env)
+{
+ return false;
+}
#endif
/*
@@ -4177,6 +4208,8 @@ int can_migrate_task(struct task_struct *p, struct lb_env *env)
* 3) too many balance attempts have failed.
*/
tsk_cache_hot = task_hot(p, rq_clock_task(env->src_rq), env->sd);
+ if (!tsk_cache_hot)
+ tsk_cache_hot = migrate_degrades_locality(p, env);
if (migrate_improves_locality(p, env)) {
#ifdef CONFIG_SCHEDSTATS
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index d9278ce2c4b4..5716929a2e3a 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -74,4 +74,12 @@ SCHED_FEAT(NUMA, false)
* balancing.
*/
SCHED_FEAT(NUMA_FAVOUR_HIGHER, true)
+
+/*
+ * NUMA_RESIST_LOWER will resist moving tasks towards nodes where a
+ * lower number of hinting faults have been recorded. As this has
+ * the potential to prevent a task ever migrating to a new node
+ * due to CPU overload it is disabled by default.
+ */
+SCHED_FEAT(NUMA_RESIST_LOWER, false)
#endif