public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
From: Quentin Perret <qperret@google.com>
To: Ingo Molnar <mingo@redhat.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
	Daniel Bristot de Oliveira <bristot@redhat.com>,
	Morten Rasmussen <morten.rasmussen@arm.com>,
	Quentin Perret <qperret@qperret.net>,
	"open list:SCHEDULER" <linux-kernel@vger.kernel.org>
Cc: kernel-team@android.com, Quentin Perret <qperret@google.com>,
	Rick Yiu <rickyiu@google.com>
Subject: [PATCH] sched/fair: Fix overutilized update in enqueue_task_fair()
Date: Thu, 12 Nov 2020 11:12:01 +0000	[thread overview]
Message-ID: <20201112111201.2081902-1-qperret@google.com> (raw)

enqueue_task_fair() attempts to skip the overutilized update for new
tasks as their util_avg is not accurate yet. However, the flag we check
to do so is overwritten earlier on in the function, which makes the
condition pretty much a nop.

Fix this by saving the flag early on.

Fixes: 2802bf3cd936 ("sched/fair: Add over-utilization/tipping point
indicator")
Reported-by: Rick Yiu <rickyiu@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
---
 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 290f9e38378c..f3ee60b92718 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5477,6 +5477,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 	struct cfs_rq *cfs_rq;
 	struct sched_entity *se = &p->se;
 	int idle_h_nr_running = task_has_idle_policy(p);
+	int task_new = !(flags & ENQUEUE_WAKEUP);
 
 	/*
 	 * The code below (indirectly) updates schedutil which looks at
@@ -5549,7 +5550,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 	 * into account, but that is not straightforward to implement,
 	 * and the following generally works well enough in practice.
 	 */
-	if (flags & ENQUEUE_WAKEUP)
+	if (!task_new)
 		update_overutilized_status(rq);
 
 enqueue_throttle:
-- 
2.29.2.222.g5d2a92d10f8-goog


             reply	other threads:[~2020-11-12 11:12 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12 11:12 Quentin Perret [this message]
2020-11-12 12:17 ` [PATCH] sched/fair: Fix overutilized update in enqueue_task_fair() Vincent Guittot
2020-11-12 12:29 ` Valentin Schneider
2020-11-12 12:38   ` Quentin Perret
2020-11-12 12:52     ` Valentin Schneider
2020-11-13  8:18 ` Peter Zijlstra
2020-11-19  9:55 ` [tip: sched/urgent] " tip-bot2 for Quentin Perret

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20201112111201.2081902-1-qperret@google.com \
    --to=qperret@google.com \
    --cc=bristot@redhat.com \
    --cc=bsegall@google.com \
    --cc=dietmar.eggemann@arm.com \
    --cc=juri.lelli@redhat.com \
    --cc=kernel-team@android.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mgorman@suse.de \
    --cc=mingo@redhat.com \
    --cc=morten.rasmussen@arm.com \
    --cc=peterz@infradead.org \
    --cc=qperret@qperret.net \
    --cc=rickyiu@google.com \
    --cc=rostedt@goodmis.org \
    --cc=vincent.guittot@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox