Re: [patch] CFS scheduler, -v19

Bill Davidsen
2007-07-12T12:40:06Z

Ingo Molnar wrote:
> * 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?
>
>
Partial answer: -10 didn't help with v16, I'll try more boost ASAP, but
power has been spotty in upstate NY, 20k+ customers with none and the
rest of us subject to "load shedding" with zero warning, and the test
machines have UPS but no generator, so I hesitate to use them while
power is unstable.
> 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.
>

Will do, you suggested dropping sched_granularity_ns to 1000000 earlier,
and that didn't do it, but I didn't change the wakeup, and will test
these values later today.

--
bill davidsen <davidsen@tmr.com>
CTO TMR Associates, Inc
Doing interesting things with small computers since 1979