Re: volanoMark regression with kernel 2.6.26-rc1

Dhaval Giani
2008-05-08T05:33:18Z

On Thu, May 08, 2008 at 01:18:34PM +0800, Zhang, Yanmin wrote:
>
> On Wed, 2008-05-07 at 23:03 +0530, Dhaval Giani wrote:
> > On Tue, May 06, 2008 at 05:22:07PM +0530, Dhaval Giani wrote:
> > > On Tue, May 06, 2008 at 10:06:30AM +0800, Zhang, Yanmin wrote:
> > > > Comparing with 2.6.25, volanoMark has big regression with kernel 2.6.26-rc1.
> > > > It's about 50% on my 8-core stoakley, 16-core tigerton, and Itanium Montecito.
> > > >
> > > > With bisect, I located below patch.
> > > >
> > > > 18d95a2832c1392a2d63227a7a6d433cb9f2037e is first bad commit
> > > > commit 18d95a2832c1392a2d63227a7a6d433cb9f2037e
> > > > Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
> > > > Date: Sat Apr 19 19:45:00 2008 +0200
> > > >
> > > > sched: fair-group: SMP-nice for group scheduling
> > > >
> > > > Implement SMP nice support for the full group hierarchy.
> > > >
> > > > If I reverse the patch with resolving some conflictions, volanoMark result could
> > > > be restored completely.
> > > >
> > >
> > > ok, that's bad. Let's get vatsa and Ingo also involved.
> > >
> >
> > Just to confirm, do you still have a performance regression with
> > !group_sched?
> I just tried it with CONFIG_GROUP_SCHED=n a moment ago. The regression becomes less than 3%.
>

Hmm. On another machine I am seeing a 10% regression, with and without
group sched. Let us work on fixing this one.

--
regards,
Dhaval