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SubjectRe: [tip:sched/urgent] sched: do not count frozen tasks toward load
On Thu 2009-04-09 05:39:32, Nathan Lynch wrote:
> Commit-ID: e3c8ca8336707062f3f7cb1cd7e6b3c753baccdd
> Gitweb: http://git.kernel.org/tip/e3c8ca8336707062f3f7cb1cd7e6b3c753baccdd
> Author: Nathan Lynch <ntl@pobox.com>
> AuthorDate: Wed, 8 Apr 2009 19:45:12 -0500
> Committer: Ingo Molnar <mingo@elte.hu>
> CommitDate: Thu, 9 Apr 2009 07:37:02 +0200
>
> sched: do not count frozen tasks toward load
>
> Freezing tasks via the cgroup freezer causes the load average to climb
> because the freezer's current implementation puts frozen tasks in
> uninterruptible sleep (D state).
>
> Some applications which perform job-scheduling functions consult the
> load average when making decisions. If a cgroup is frozen, the load
> average does not provide a useful measure of the system's utilization
> to such applications. This is especially inconvenient if the job
> scheduler employs the cgroup freezer as a mechanism for preempting low
> priority jobs. Contrast this with using SIGSTOP for the same purpose:
> the stopped tasks do not count toward system load.
>
> Change task_contributes_to_load() to return false if the task is
> frozen. This results in /proc/loadavg behavior that better meets
> users' expectations.
>
> Signed-off-by: Nathan Lynch <ntl@pobox.com>
> Acked-by: Andrew Morton <akpm@linux-foundation.org>
> Acked-by: Nigel Cunningham <nigel@tuxonice.net>
> Tested-by: Nigel Cunningham <nigel@tuxonice.net>
> Cc: <stable@kernel.org>
> Cc: containers@lists.linux-foundation.org
> Cc: linux-pm@lists.linux-foundation.org
> Cc: Matt Helsley <matthltc@us.ibm.com>
> LKML-Reference: <20090408194512.47a99b95@manatee.lan>
> Signed-off-by: Ingo Molnar <mingo@elte.hu>

Acked-by: Pavel Machek <pavel@ucw.cz>

--
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(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html


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