Subject: Re: VolanoMark regression with 2.6.27-rc1
From: "Zhang, Yanmin" <yanmin_zhang@linux.intel.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>
In-Reply-To: <1217489949.8157.78.camel@twins>
References: <1217474425.25608.150.camel@ymzhang>
	 <1217489463.25608.157.camel@ymzhang>  <1217489949.8157.78.camel@twins>
Content-Type: text/plain
Date: Thu, 31 Jul 2008 15:49:20 +0800
Message-Id: <1217490560.25608.168.camel@ymzhang>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2470
Lines: 62


On Thu, 2008-07-31 at 09:39 +0200, Peter Zijlstra wrote:
> On Thu, 2008-07-31 at 15:31 +0800, Zhang, Yanmin wrote:
> > On Thu, 2008-07-31 at 11:20 +0800, Zhang, Yanmin wrote:
> > > Ingo,
> > > 
> > > volanoMark has regression with 2.6.27-rc1.
> > > 1) 70% on 16-core tigerton;
> > > 2) 18% on a new multi-core+HT mahcine;
> > > 
> > > I tried to use git bisect to locate the root cause, but git bisect always went
> > > back to 2.6.26. Then, I used my mechanical bisect script linearly to locate below commit:
> > > 
> > > commit 82638844d9a8581bbf33201cc209a14876eca167
> > > Merge: 9982fbf... 63cf13b...
> > > Author: Ingo Molnar <mingo@elte.hu>
> > > Date:   Wed Jul 16 00:29:07 2008 +0200
> > > 
> > >     Merge branch 'linus' into cpus4096
> > > 
> > >     Conflicts:
> > > 
> > >         arch/x86/xen/smp.c
> > >         kernel/sched_rt.c
> > >         net/iucv/iucv.c
> > > 
> > >     Signed-off-by: Ingo Molnar <mingo@elte.hu>
> > > 
> > > 
> > > 
> > > But if I use 'git show 82638844d9a8581bbf33201cc209a14876eca167', it looks like I could only
> > > get a part of the patch. If I use web to acces the commit, I could get a big patch. As it's
> > > a merge, what're commit numbers of the subpatches?
> > > 
> > > 
> > > BTW, sysbench+mysql(oltp readonly) has about 15% regression, but git bisect looks crazy again.
> 
> > Oh, it looks like they are the old issues in 2.6.26-rc1 and the 2 patches were reverted before 2.6.26.
> > New patches are merged into 2.6.27-rc1, but the issues are still not resolved clearly.
> > http://www.uwsg.iu.edu/hypermail/linux/kernel/0805.2/1148.html.
> 
> The new smp-group stuff doesn't remotely look like what was in .26
> 
> Also, on my quad (admittedly smaller than your machines) both volano and
> sysbench didn't regress anymore - where they clearly did with the code
> reverted from .26.
The regression I reported exists on:
1) 8-core+HT(totally 16 logical processor) tulsa: 40% regression with volano, 8% with oltp;
2) 8-core+HT Montvale Itanium: 9% regression with volano; 8% with oltp;
3) 16-core tigerton: %70 with volano, %18 with oltp;
4) 8-core stoakley: %15 with oltp, testing failed with volanoMark.

So the issues are popular on different architectures.

yanmin


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/