Messages in this thread | | | Date | Thu, 10 Sep 2009 08:53:06 +0200 | From | Ingo Molnar <> | Subject | Re: Epic regression in throughput since v2.6.23 |
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* Serge Belyshev <belyshev@depni.sinp.msu.ru> wrote:
> Ingo Molnar <mingo@elte.hu> writes: > > > Thanks! > > > > I think we found the reason for that regression - would you mind > > to re-test with latest -tip, e157986 or later? > > > > If that works for you i'll describe our theory. > > > > Good job -- seems to work, thanks. Regression is still about 3% > though: http://img3.imageshack.us/img3/5335/epicbfstip.png
Ok, thanks for the update. The problem is that i've run out of testsystems that can reproduce this. So we need your help to debug this directly ...
A good start would be to post the -tip versus BFS "perf stat" measurement results:
perf stat --repeat 3 make -j4 bzImage
And also the -j8 perf stat result, so that we can see what the difference is between -j4 and -j8.
Note: please check out latest tip and do:
cd tools/perf/ make -j install
To pick up the latest 'perf' tool. In particular the precision of --repeat has been improved recently so you want that binary from -tip even if you measure vanilla .31 or .31 based BFS.
Also, it would be nice if you could send me your kernel config - maybe it's some config detail that keeps me from being able to reproduce these results. I havent seen a link to a config in your mails (maybe i missed it - these threads are voluminous).
Ingo
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