linux-kernel - [tip: sched/core] sched/fair: calculate delta runnable load only when it's needed

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Date:   Fri, 17 Jan 2020 10:08:41 -0000
From:   "tip-bot2 for Peng Wang" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Peng Wang <rocking@...ux.alibaba.com>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        x86 <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>
Subject: [tip: sched/core] sched/fair: calculate delta runnable load only when
 it's needed

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     fe71bbb21ee14160f73f81b113d71145327a1c0d
Gitweb:        https://git.kernel.org/tip/fe71bbb21ee14160f73f81b113d71145327a1c0d
Author:        Peng Wang <rocking@...ux.alibaba.com>
AuthorDate:    Fri, 03 Jan 2020 19:44:00 +08:00
Committer:     Peter Zijlstra <peterz@...radead.org>
CommitterDate: Fri, 17 Jan 2020 10:19:21 +01:00

sched/fair: calculate delta runnable load only when it's needed

Move the code of calculation for delta_sum/delta_avg to where
it is really needed to be done.

Signed-off-by: Peng Wang <rocking@...ux.alibaba.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
Link: https://lkml.kernel.org/r/20200103114400.17668-1-rocking@linux.alibaba.com
---
 kernel/sched/fair.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d292883..32c5421 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3366,16 +3366,17 @@ update_tg_cfs_runnable(struct cfs_rq *cfs_rq, struct sched_entity *se, struct cf
 
 	runnable_load_sum = (s64)se_runnable(se) * runnable_sum;
 	runnable_load_avg = div_s64(runnable_load_sum, LOAD_AVG_MAX);
-	delta_sum = runnable_load_sum - se_weight(se) * se->avg.runnable_load_sum;
-	delta_avg = runnable_load_avg - se->avg.runnable_load_avg;
-
-	se->avg.runnable_load_sum = runnable_sum;
-	se->avg.runnable_load_avg = runnable_load_avg;
 
 	if (se->on_rq) {
+		delta_sum = runnable_load_sum -
+				se_weight(se) * se->avg.runnable_load_sum;
+		delta_avg = runnable_load_avg - se->avg.runnable_load_avg;
 		add_positive(&cfs_rq->avg.runnable_load_avg, delta_avg);
 		add_positive(&cfs_rq->avg.runnable_load_sum, delta_sum);
 	}
+
+	se->avg.runnable_load_sum = runnable_sum;
+	se->avg.runnable_load_avg = runnable_load_avg;
 }
 
 static inline void add_tg_cfs_propagate(struct cfs_rq *cfs_rq, long runnable_sum)