[PATCH 3/4] sched: Comment on why sync wakeups try to run on the current CPU

[Mel Gorman]

The sync wakeup logic in wake_affine_idle deserves a short description.

Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
---
 kernel/sched/fair.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 392e08b364bd..95b1145bc38d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5737,6 +5737,11 @@ wake_affine_idle(int this_cpu, int prev_cpu, int sync)
 static int
 wake_affine_sync(int this_cpu, int sync)
 {
+	/*
+	 * Consider stacking tasks if it's a sync wakeup and there is only
+	 * one task on the runqueue. sync wakesups are expected to sleep
+	 * either immediately or shortly after the wakeup.
+	 */
 	if (sync && cpu_rq(this_cpu)->nr_running == 1)
 		return this_cpu;
 
-- 
2.15.0