From: Tao Zhou <ouwen210@hotmail.com>
Date: Thu, 19 Mar 2020 09:46:28 +0000
Subject: [PATCH] sched/fair: fix condition of avg_load calculation

References: bnc#1155798 (CPU scheduler functional and performance backports)
Patch-mainline: v5.7-rc1
Git-commit: 6c8116c914b65be5e4d6f66d69c8142eb0648c22

In update_sg_wakeup_stats(), the comment says:

Computing avg_load makes sense only when group is fully
busy or overloaded.

But, the code below this comment does not check like this.

From reading the code about avg_load in other functions, I
confirm that avg_load should be calculated in fully busy or
overloaded case. The comment is correct and the checking
condition is wrong. So, change that condition.

Fixes: 57abff067a08 ("sched/fair: Rework find_idlest_group()")
Signed-off-by: Tao Zhou <ouwen210@hotmail.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
 kernel/sched/fair.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 83a52eb4f67d..facda53a7264 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8552,7 +8552,8 @@ static inline void update_sg_wakeup_stats(struct sched_domain *sd,
 	 * Computing avg_load makes sense only when group is fully busy or
 	 * overloaded
 	 */
-	if (sgs->group_type < group_fully_busy)
+	if (sgs->group_type == group_fully_busy ||
+		sgs->group_type == group_overloaded)
 		sgs->avg_load = (sgs->group_load * SCHED_CAPACITY_SCALE) /
 				sgs->group_capacity;
 }