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Message-ID: <29495f1d0703131809i6f76e409q2c505a33f0b23a8d@mail.gmail.com>
Date: Tue, 13 Mar 2007 18:09:42 -0700
From: "Nish Aravamudan" <nish.aravamudan@gmail.com>
To: "Eric Dumazet" <dada1@cosmosbay.com>
Subject: Re: SMP performance degradation with sysbench
Cc: "Anton Blanchard" <anton@samba.org>,
       "Nick Piggin" <nickpiggin@yahoo.com.au>,
       "Rik van Riel" <riel@redhat.com>,
       "Lorenzo Allegrucci" <l_allegrucci@yahoo.it>,
       linux-kernel@vger.kernel.org, "Ingo Molnar" <mingo@elte.hu>,
       "Suparna Bhattacharya" <suparna@in.ibm.com>,
       "Jens Axboe" <jens.axboe@oracle.com>
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On 3/13/07, Eric Dumazet <dada1@cosmosbay.com> wrote:
> Nish Aravamudan a écrit :
> > On 3/12/07, Anton Blanchard <anton@samba.org> wrote:
> >>
> >> Hi Nick,
> >>
> >> > Anyway, I'll keep experimenting. If anyone from MySQL wants to help
> >> look
> >> > at this, send me a mail (eg. especially with the sched_setscheduler
> >> issue,
> >> > you might be able to do something better).
> >>
> >> I took a look at this today and figured Id document it:
> >>
> >> http://ozlabs.org/~anton/linux/sysbench/
> >>
> >> Bottom line: it looks like issues in the glibc malloc library, replacing
> >> it with the google malloc library fixes the negative scaling:
> >>
> >> # apt-get install libgoogle-perftools0
> >> # LD_PRELOAD=/usr/lib/libtcmalloc.so /usr/sbin/mysqld
> >
> > Quick datapoint, still collecting data and trying to verify it's
> > always the case: on my 8-way Xeon, I'm actually seeing *much* worse
> > performance with libtcmalloc.so compared to mainline. Am generating
> > graphs and such still, but maybe someone else with x86_64 hardware
> > could try the google PRELOAD and see if it helps/hurts (to rule out
> > tester stupidity)?
>
> I wish I had a 8-way test platform :)
>
> Anyway, could you post some oprofile results ?

Hopefully soon -- want to still make sure I'm not doing something
dumb. Am also hoping to get some of the gdb backtraces like Anton had.

Thanks,
Nish