linux-kernel - Re: [PATCH 1/2] sched/fair: Fix how load gets propagated from cfs_rq to its sched

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Message-ID: <20170502200028.GA5335@htj.duckdns.org>
Date:   Tue, 2 May 2017 16:00:28 -0400
From:   Tejun Heo <tj@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        Ingo Molnar <mingo@...hat.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Galbraith <efault@....de>, Paul Turner <pjt@...gle.com>,
        Chris Mason <clm@...com>, kernel-team@...com
Subject: Re: [PATCH 1/2] sched/fair: Fix how load gets propagated from cfs_rq
 to its sched_entity

Hello, Peter.

Your changes need the following fix patch.  With the fix and
"sched/fair: Always propagate runnable_load_avg" applied, it seems to
work fine.  The propagated number is a bit different but I don't see
noticeable difference in behavior and the new number seems to better
represent what we need.

Thanks.
---
 kernel/sched/fair.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -2645,7 +2645,8 @@ enum shares_type {
 #ifdef CONFIG_FAIR_GROUP_SCHED
 # ifdef CONFIG_SMP
 static long
-calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg, enum shares_type)
+calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg,
+		enum shares_type shares_type)
 {
 	long tg_weight, tg_shares, load, shares;
 
@@ -2705,7 +2706,7 @@ calc_cfs_shares(struct cfs_rq *cfs_rq, s
 }
 # else /* CONFIG_SMP */
 static inline long
-calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg, enum shares_type)
+calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg, enum shares_type shares_type)
 {
 	return tg->shares;
 }
@@ -3104,7 +3105,7 @@ static inline void
 update_tg_cfs_load(struct cfs_rq *cfs_rq, struct sched_entity *se)
 {
 	struct cfs_rq *gcfs_rq = group_cfs_rq(se);
-	long delta, load = calc_cfs_shares(gcfs_rq, gcfs_rq->tg, shares_runnable);
+	long delta, load = scale_load_down(calc_cfs_shares(gcfs_rq, gcfs_rq->tg, shares_runnable));
 
 	delta = load - se->avg.load_avg;