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    SubjectRe: aim7 -30% regression in 2.6.24-rc1
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    On Mon, 2007-10-29 at 10:22 +0800, Zhang, Yanmin wrote:
    > 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.
    I ran git bisect with kernel version as the tag. It looks like git will
    be crazy sometimes. So I checked ChangeLog and used the number tag to replace
    the kernel version and retested it.

    It looks like at least 2 patches were responsible for the regression. I'm
    doing sub-bisect now.

    I could find aim7 regression on all my testing machines although the regression
    percentage is different.

    Machine regression
    8-core stoakley 30%
    16-core tigerton 6%
    tulsa(dual-core+HT, 16 logical cpu) 20%

    -yanmin
    -
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