Messages in this thread | | | Subject | Re: VolanoMark regression with 2.6.27-rc1 | From | "Zhang, Yanmin" <> | Date | Fri, 01 Aug 2008 08:39:14 +0800 |
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On Thu, 2008-07-31 at 15:49 +0800, Zhang, Yanmin wrote: > 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. I know kernel needs the features and it might not be a good idea to reject them over and over again. I will collect more data on tigerton and try to optimize it.
-yanmin
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