[PATCH v2 1/8] sched/fair: Update affine statistics when needed

[Srikar Dronamraju]

wake_affine_idle() can return prev_cpu. Even in such a scenario,
scheduler was going ahead and updating schedstats related to wake
affine. i.e even if the task is not moved across LLC domains,
schedstats would have accounted.

Hence add a check before updating schedstats.

Cc: LKML <linux-kernel@xxxxxxxxxxxxxxx>
Cc: Gautham R Shenoy <ego@xxxxxxxxxxxxxxxxxx>
Cc: Parth Shah <parth@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Valentin Schneider <valentin.schneider@xxxxxxx>
Cc: Dietmar Eggemann <dietmar.eggemann@xxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Vincent Guittot <vincent.guittot@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Signed-off-by: Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx>
---
 kernel/sched/fair.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 794c2cb945f8..a258a84cfdfd 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5884,8 +5884,10 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p,
 	if (target == nr_cpumask_bits)
 		return prev_cpu;
 
-	schedstat_inc(sd->ttwu_move_affine);
-	schedstat_inc(p->se.statistics.nr_wakeups_affine);
+	if (!cpus_share_cache(prev_cpu, target)) {
+		schedstat_inc(sd->ttwu_move_affine);
+		schedstat_inc(p->se.statistics.nr_wakeups_affine);
+	}
 	return target;
 }
 
-- 
2.18.2