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Message-ID: <20091003104723.GC15919@elte.hu>
Date: Sat, 3 Oct 2009 12:47:23 +0200
From: Ingo Molnar <mingo@...e.hu>
To: drago01 <drago01@...il.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Mike Galbraith <efault@....de>
Cc: kernel list <linux-kernel@...r.kernel.org>, mingo@...hat.com,
Chuck Ebbert <cebbert@...hat.com>
Subject: Re: sched regression introduced by NO_NEW_FAIR_SLEEPERS
* drago01 <drago01@...il.com> wrote:
> 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.
> >
>
> With "NEW_FAIR_SLEEPERS" I can even run 100(!) "md5sum" task without
> any effect on interactivity. (still have not found a number of tasks
> needed to make the system unresponsive as with 8 with
> "NO_NEW_FAIR_SLEEPERS".
Can you try the latest -tip tree please:
http://people.redhat.com/mingo/tip.git/README
There we default to FAIR_SLEEPERS + GENTLE_FAIR_SLEEPERS - which should
give much of the new-fair-sleepers advantage.
There's also a new tool, 'perf sched', which you can install via:
cd tools/perf/
make -j install
And use like this to measure latencies in the system:
$ perf sched record sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.059 MB perf.data (~2563 samples) ]
$ perf sched latency
-----------------------------------------------------------------------------------------
Task | Runtime ms | Switches | Average delay ms | Maximum delay ms |
-----------------------------------------------------------------------------------------
events/12:47 | 0.007 ms | 1 | avg: 0.054 ms | max: 0.054 ms |
events/2:37 | 0.128 ms | 1 | avg: 0.016 ms | max: 0.016 ms |
at-spi-registry:3292 | 0.752 ms | 20 | avg: 0.015 ms | max: 0.023 ms |
Xorg:3161 | 0.519 ms | 20 | avg: 0.015 ms | max: 0.024 ms |
perf:19070 | 21.241 ms | 5 | avg: 0.012 ms | max: 0.019 ms |
events/1:36 | 0.009 ms | 1 | avg: 0.009 ms | max: 0.009 ms |
hald-addon-stor:2790 | 0.204 ms | 9 | avg: 0.009 ms | max: 0.011 ms |
scsi_eh_5:1072 | 0.200 ms | 12 | avg: 0.009 ms | max: 0.009 ms |
events/0:35 | 0.007 ms | 1 | avg: 0.008 ms | max: 0.008 ms |
ksoftirqd/12:28 | 0.088 ms | 5 | avg: 0.005 ms | max: 0.009 ms |
sleep:19071 | 0.668 ms | 3 | avg: 0.005 ms | max: 0.008 ms |
migration/13:29 | 0.000 ms | 1 | avg: 0.003 ms | max: 0.003 ms |
-----------------------------------------------------------------------------------------
TOTAL: | 23.824 ms | 79 |
---------------------------------------------------
Thanks,
Ingo
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