Re: [patch] CFS scheduler, -v19

[Bill Davidsen <davidsen@tmr.com>]

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

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