Re: aim7 -30% regression in 2.6.24-rc1

["Zhang, Yanmin" <yanmin_zhang@linux.intel.com>]

On Fri, 2007-10-26 at 13:23 +0200, Ingo Molnar wrote:
> * Zhang, Yanmin <yanmin_zhang@linux.intel.com> wrote:
> 
> > I tested 2.6.24-rc1 on my x86_64 machine which has 2 quad-core processors.
> > 
> > Comparing with 2.6.23, aim7 has about -30% regression. I did a bisect 
> > and found patch 
> > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=b5869ce7f68b233ceb81465a7644be0d9a5f3dbb 
> > caused the issue.
> 
> weird, that's a commit diff - i.e. it changes no code.
I got the tag from #git log. As for above link, I just added prior http address,
so readers could check the patch by clicking.

> 
> > kbuild/SPECjbb2000/SPECjbb2005 also has big regressions. On my another 
> > tigerton machine (4 quad-core processors), SPECjbb2005 has more than 
> > -40% regression. I didn't do a bisect on such benchmark testing, but I 
> > suspect the root cause is like aim7's.
> 
> these two commits might be relevant:
> 
>   7a6c6bcee029a978f866511d6e41dbc7301fde4c
I did a quick testing. This patch has no impact.

>   95dbb421d12fdd9796ed153853daf3679809274f
Above big patch doesn't include this one, which means if I do
'git checkout b5869ce7f68b233ceb81465a7644be0d9a5f3dbb', the kernel doesn't include
95dbb421d12fdd9796ed153853daf3679809274f.

> 
> but a bisection result would be the best info.
I will do a bisect between 2.6.23 and tag 9c63d9c021f375a2708ad79043d6f4dd1291a085.

-yanmin