Re: [ck] Re: SD still better than CFS for 3d ?(was Re: 2.6.23-rc1)

Miguel Figueiredo
2007-07-31T13:33:15Z

Em Terça, 31 de Julho de 2007 14:16, Matthew Hawkins escreveu:
> On 7/31/07, Ingo Molnar <mingo@elte.hu> wrote:
> > * Kenneth Prugh <ken69267@gmail.com> wrote:
> > > CFS generally seemed a lot smoother as the load increased, while SD
> > > broke down to a highly unstable fps count that fluctuated massively
> > > around the third loop. Seems like I will stick to CFS for gaming now.
>
> My experience was quite similar. I noticed after launching the second
> loop that the FPS stuck down to 15 for about 20 seconds, then climbed
> back up to 48. After that it went rapidly downhill. This is similar
> to other benchmarks I've done of SD versus CFS in the past. At a
> "normal" load they're fairly similar but SD breaks down under
> pressure.
> The only other thing of interest is that the -ck kernel had the WM
> menus appear in about 3 seconds rather than 5-8 under the other two.
>
> Game: Nexuiz 2.3
> OpenGL 2.0 shaders on
> Vertex Buffer Objects on
> Show FPS on
> ultimate quality
> 1024x768
>
> 2.6.23-git
> 0 48
> 1 48
> 2 48
> 3 48
> 4 40
> 5 38
> 6 33
> 7 28
> 8 22
> 9 22
> 10 18
>
> 2.6.22.1-ck
> 0 48
> 1 48
> 2 48
> 3 12
> 4 6
> 5 6
> 6 5
> 7 4
> 8 3
> 9 3
> 10 2
>
> 2.6.22.1-cfs-v19.1+ckbits [*]
> 0 48
> 1 48
> 2 48
> 3 46
> 4 45
> 5 43
> 6 36
> 7 32
> 8 25
> 9 24
> 10 24
>
> [*] This kernel has the cfq-* and mm-* patches from -ck applied, and
> the above-background-load function from pre-SD ck patchsets (or
> 2.6.23-git)

CFS does not requeue_task() on SCHED_YIELD (used by graphic drivers) as until
2.6.22 and -ck. Please try this hack [1] that makes -ck to behave like CFS
then you are comparing apples to apples.

Details on the SCHED_YIELD implementation on [2]. Please correct it if it's
wrong.

1 - http://www.debianpt.org/~elmig/pool/kernel/20070731/sched_yield_hack.patch
2 - http://bhhdoa.org.au/pipermail/ck/2007-July/008297.html

--

Com os melhores cumprimentos/Best regards,

Miguel Figueiredo