linux-kernel - Re: sched regression introduced by NO_NEW_FAIR

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Date:	Sun, 27 Sep 2009 22:06:21 +0200
From:	drago01 <drago01@...il.com>
To:	kernel list <linux-kernel@...r.kernel.org>
Cc:	mingo@...hat.com, Chuck Ebbert <cebbert@...hat.com>
Subject: Re: sched regression introduced by NO_NEW_FAIR_SLEEPERS

On Sun, Sep 27, 2009 at 9:47 PM, drago01 <drago01@...il.com> wrote:
> Hi,
>
> Chuck has backported some scheduler patches from 2.6.32 to the fedora kernel.
>
> I did the following test to test the new scheduler (cpu is a core i7
> 920 4 cores + HT).
>
> run 8 "md5sum /dev/urandom" task and try to use the desktop (compiz).
>
> The result was that moving windows or rotating the cube is very slow.
> (same happens with pure metacity but is is worse in compiz).
>
> Mounting debugfs and doing "echo NEW_FAIR_SLEEPERS > sched_features"
> results into a useable desktop while the 8 md5sum tasks are running
> (ie. the system behaves as if they where not running at all from an
> interactivity pov).
>
>
> P.S: please CC me when replying.
>

OK, tried on a "vanilla 2.6.30.8 scheduler" I can reproduce this by
toggling  NEW_FAIR_SLEEPERS on/off. (So it was not a side effect of
other scheduler patches)
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