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-rw-r--r--kernel/sched/core.c11
-rw-r--r--kernel/sched/fair.c2
-rw-r--r--kernel/sched/features.h5
3 files changed, 14 insertions, 4 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 956383844116..3b31fc05a0f1 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3287,10 +3287,15 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
struct task_struct *p;
/*
- * Optimization: we know that if all tasks are in
- * the fair class we can call that function directly:
+ * Optimization: we know that if all tasks are in the fair class we can
+ * call that function directly, but only if the @prev task wasn't of a
+ * higher scheduling class, because otherwise those loose the
+ * opportunity to pull in more work from other CPUs.
*/
- if (likely(rq->nr_running == rq->cfs.h_nr_running)) {
+ if (likely((prev->sched_class == &idle_sched_class ||
+ prev->sched_class == &fair_sched_class) &&
+ rq->nr_running == rq->cfs.h_nr_running)) {
+
p = fair_sched_class.pick_next_task(rq, prev, rf);
if (unlikely(p == RETRY_TASK))
goto again;
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3e88b35ac157..dea138964b91 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5799,7 +5799,7 @@ static int select_idle_cpu(struct task_struct *p, struct sched_domain *sd, int t
* Due to large variance we need a large fuzz factor; hackbench in
* particularly is sensitive here.
*/
- if ((avg_idle / 512) < avg_cost)
+ if (sched_feat(SIS_AVG_CPU) && (avg_idle / 512) < avg_cost)
return -1;
time = local_clock();
diff --git a/kernel/sched/features.h b/kernel/sched/features.h
index 69631fa46c2f..1b3c8189b286 100644
--- a/kernel/sched/features.h
+++ b/kernel/sched/features.h
@@ -51,6 +51,11 @@ SCHED_FEAT(NONTASK_CAPACITY, true)
*/
SCHED_FEAT(TTWU_QUEUE, true)
+/*
+ * When doing wakeups, attempt to limit superfluous scans of the LLC domain.
+ */
+SCHED_FEAT(SIS_AVG_CPU, false)
+
#ifdef HAVE_RT_PUSH_IPI
/*
* In order to avoid a thundering herd attack of CPUs that are