Re: [patch] CFS scheduler, -v19

Ingo Molnar
2007-07-11T20:57:13Z

* Bill Davidsen <davidsen@tmr.com> wrote:

> > I've taken mainline git tree (freshly integrated CFS!) out for a
> > multimedia spin. I tested watching movies and listenign to music in
> > the presence of various sleep/burn loads, pure burn loads, and mixed
> > loads. All was peachy here.. I saw no frame drops or sound skips or
> > other artifacts under any load where the processor could possibly
> > meet demand.
>
> I would agree with preliminary testing, save that if you get a lot of
> processes updating the screen at once, there seems to be a notable
> case of processes getting no CPU for 100-300ms, followed by a lot of
> CPU.
>
> I see this clearly with the "glitch1" test with four scrolling xterms
> and glxgears, but also watching videos with little busy processes on
> the screen. The only version where I never see this in test or with
> real use is cfs-v13.

just as a test, does this go away if you:

renice -20 pidof `Xorg`

i.e. is this connected to the way X is scheduled?

Another thing to check would be whether it goes away if you set the
granularity to some really finegrained value:

echo 0 > /proc/sys/kernel/sched_wakeup_granularity_ns
echo 500000 > /proc/sys/kernel/sched_granularity_ns

this really pushes things - but it tests the theory whether this is
related to granularity.

Ingo