From: Yuyang Du <yuyang.du@intel.com>
To: Steve Muckle <steve.muckle@linaro.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Morten Rasmussen <morten.rasmussen@arm.com>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Patrick Bellasi <patrick.bellasi@arm.com>,
Juri Lelli <Juri.Lelli@arm.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: PELT initial task load and wake_up_new_task()
Date: Mon, 14 Dec 2015 03:13:20 +0800 [thread overview]
Message-ID: <20151213191319.GA28098@intel.com> (raw)
In-Reply-To: <566B8009.2090006@linaro.org>
Hi Steve,
On Fri, Dec 11, 2015 at 06:01:45PM -0800, Steve Muckle wrote:
> In init_entity_runnable_average() the last_update_time is initialized to
> zero. The task is given max load and utilization as a pessimistic
> initial estimate.
>
> But if in wake_up_new_task() the task is placed on a CPU other than
> where it was created, __update_load_avg() will be called via
> set_task_cpu() -> migrate_task_rq_fair() -> remove_entity_load_avg().
>
> Since last_update_time is zero the delta will be huge and the task's
> load will be entirely decayed away before it is enqueued at the
> destination CPU.
Since the new task's last_update_time is equal to 0, it will not be decayed.
next prev parent reply other threads:[~2015-12-14 2:59 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-12 2:01 PELT initial task load and wake_up_new_task() Steve Muckle
2015-12-13 19:13 ` Yuyang Du [this message]
2015-12-15 0:41 ` Steve Muckle
2015-12-15 2:24 ` Yuyang Du
2015-12-15 18:45 ` Steve Muckle
2015-12-15 23:55 ` Yuyang Du
2015-12-16 7:58 ` [PATCH] sched: Fix new task's load avg removed from source CPU in kbuild test robot
2015-12-17 2:50 ` PELT initial task load and wake_up_new_task() Steve Muckle
2015-12-16 23:34 ` Yuyang Du
2015-12-17 9:43 ` Peter Zijlstra
2015-12-17 2:16 ` Yuyang Du
2016-01-06 18:49 ` [tip:sched/core] sched/fair: Fix new task' s load avg removed from source CPU in wake_up_new_task() tip-bot for Yuyang Du
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=20151213191319.GA28098@intel.com \
--to=yuyang.du@intel.com \
--cc=Juri.Lelli@arm.com \
--cc=dietmar.eggemann@arm.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=morten.rasmussen@arm.com \
--cc=patrick.bellasi@arm.com \
--cc=peterz@infradead.org \
--cc=steve.muckle@linaro.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.