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Message-ID: <29495f1d0703131736l74a63c15n94f03527d7e63500@mail.gmail.com>
Date: Tue, 13 Mar 2007 17:36:36 -0700
From: "Nish Aravamudan" <nish.aravamudan@gmail.com>
To: "Anton Blanchard" <anton@samba.org>
Subject: Re: SMP performance degradation with sysbench
Cc: "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 3/12/07, 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)?

Thanks,
Nish