linux-kernel - Re: Serious performance regression in Wine applications and Linux 2.6.24.*

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Date:	Wed, 02 Apr 2008 05:40:00 -0700
From:	"Kai" <epimetreus@...tmail.fm>
To:	linux-kernel@...r.kernel.org
Subject: Re: Serious performance regression in Wine applications and Linux  
   2.6.24.*

On Tue, 25 Mar 2008 08:49:13 -0700, "Ray Lee" <ray-lk@...rabbit.org>
said:
> On Tue, Mar 25, 2008 at 5:12 AM, Kai <epimetreus@...tmail.fm> wrote:
> >
> >  On Sat, 22 Mar 2008 21:47:52 -0700, "Ray Lee" <ray-lk@...rabbit.org>
> >  said:
> >
> >
> > > On Sat, Mar 22, 2008 at 7:49 PM, Kai <epimetreus@...tmail.fm> wrote:
> >  > > Performance degrades by about 60% when I run Wine under any of the
> >  > >  2.6.24.* kernels. Attached are the output of lspci -vv and the two
> >  > >  config files of each kernel.
> >  > >
> >  > >  I upgraded to 2.6.24, back to 2.6.23.(not sure), then tried 2.6.24.1 and
> >  > >  2.6.24.3 and the issue is present in both; it's severe enough that Wine
> >  > >  apps are virtually unusable for me with this version of the kernel; I'm
> >  > >  having to use 2.6.23 until this somehow is resolved.
> >  > >
> >  > >  I'd like some help figuring out why this performance regression exists,
> >  > >  and what can be done to mitigate it.
> >  >
> >  > As wine has a 'wineserver' running in a separate process, it may be
> >  > related to scheduler changes.
> >  >
> >  > Regardless, if you have the time, please retest using he latest git
> >  > head (or nightly snapshot), and see if the performance regression is
> >  > still there, and report back. (There have been a lot of changes
> >  > between 2.6.24 and current git head that impact the scheduler.)
> >  >
> >  > Please ensure that the fair group scheduler is disabled in your tests
> >  > (just as you have in your 2.6.24 config you attached).
> >
> >  As mentioned in another response, it was happening as recently as
> >  2.6.25-rc6-git7; I'm currently performing a git bisect between 2.6.23
> >  and 2.6.24, unless someone has a better idea; it seems my best option,
> >  as I'm not really very experienced with kernel hacking or debugging.
> >
>
> Andi's idea of looking for excessive context switches is good -- I
> didn't see a response to that one. Other than that, if you're only
> noticing the issue in 3d games, then it could be several things (not
> just the scheduler). Even just a few bisects (or testings of nightly
> snapshots) would help narrow it down.
>
> Ray

I'm going to do tests with his script right now; I'm moving, so testing
is a bit delayed right now.
The game is actually 2D, not 3D, and sprite based. There is some
(voxel?) based 3d combat, but the bug affects even the 2d map.

Preliminarily, I'm going to guess it's the CPU scheduler stuff, since I
have noticed that any build which includes it also has the problem, but
I can't say that definitively until I test a little more; I'll have more
feedback soon.

Apologies for the delay,

-Kai
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