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From: Eric Dumazet <dada1@cosmosbay.com>
To: Anton Blanchard <anton@samba.org>
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>
Subject: Re: SMP performance degradation with sysbench
Date: Tue, 13 Mar 2007 07:00:27 +0100	[thread overview]
Message-ID: <45F63DFB.9040302@cosmosbay.com> (raw)
In-Reply-To: <20070312220042.GA807@kryten>

Anton Blanchard a écrit :
>  
> 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

Hi Anton, thanks for the report.
glibc has certainly many scalability problems.

One of the known problem is its (ab)use of mmap() to allocate one (yes : one 
!) page every time you fopen() a file. And then a munmap() at fclose() time.


mmap()/munmap() should be avoided as hell in multithreaded programs.

  parent reply	other threads:[~2007-03-13  6:01 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-25 17:44 SMP performance degradation with sysbench Lorenzo Allegrucci
2007-02-25 23:46 ` Rik van Riel
2007-02-26 13:36   ` Nick Piggin
2007-02-26 13:41     ` Nick Piggin
2007-02-26 22:04     ` Pete Harlan
2007-02-26 22:36       ` Dave Jones
2007-02-27  0:32         ` Hiro Yoshioka
2007-02-27  0:43           ` Rik van Riel
2007-02-27  4:03             ` Hiro Yoshioka
2007-02-27  4:31               ` Rik van Riel
2007-02-27  8:14                 ` J.A. Magallón
2007-02-27 14:02                   ` Rik van Riel
2007-02-27 14:56                     ` Paulo Marques
2007-02-27 20:40                       ` Nish Aravamudan
2007-02-28  2:21                       ` Bill Davidsen
2007-02-28  2:52                         ` Nish Aravamudan
2007-03-01  0:20                           ` Nish Aravamudan
2007-02-27 19:05                     ` Lorenzo Allegrucci
2007-03-01 16:57                       ` Lorenzo Allegrucci
2007-02-28  1:27     ` Nish Aravamudan
2007-02-28  2:22       ` Nick Piggin
2007-02-28  2:51         ` Nish Aravamudan
2007-03-12 22:00     ` Anton Blanchard
2007-03-13  5:11       ` Nick Piggin
2007-03-13  9:45         ` Andrea Arcangeli
2007-03-13 10:06           ` Nick Piggin
2007-03-13 10:31             ` Andrea Arcangeli
2007-03-13 10:37               ` Nick Piggin
2007-03-13 10:57                 ` Andrea Arcangeli
2007-03-13 11:12                   ` Nick Piggin
2007-03-13 11:40                     ` Eric Dumazet
2007-03-13 11:56                       ` Nick Piggin
2007-03-13 11:42                     ` Andrea Arcangeli
2007-03-13 12:02                       ` Eric Dumazet
2007-03-13 12:27                         ` Jakub Jelinek
2007-03-13 12:08                       ` Nick Piggin
2007-03-14 23:33                         ` Siddha, Suresh B
2007-03-20  2:29                           ` Zhang, Yanmin
2007-04-02  2:59                             ` Zhang, Yanmin
2007-03-13  6:00       ` Eric Dumazet [this message]
2007-03-14  0:36       ` Nish Aravamudan
2007-03-14  1:00         ` Eric Dumazet
2007-03-14  1:09           ` Nish Aravamudan
     [not found] <fa.V3M3ZgXL+lFlIyhx43YxCU/JFUk@ifi.uio.no>
     [not found] ` <fa.ciL5lzdfskdJHJPgn+UVCHt/9EM@ifi.uio.no>
     [not found]   ` <fa.2ABbHhyCbp3Fx7hSE/Gr0SuzFvw@ifi.uio.no>
     [not found]     ` <fa.oaZk6Aiqd8gyZNsj7+m+w9MibhU@ifi.uio.no>
     [not found]       ` <fa.RjX9Y4ckjRCle5L+uWNdd0snOio@ifi.uio.no>
     [not found]         ` <fa.XocsudxlGplKh0kloTtA0juPwtA@ifi.uio.no>
2007-02-28  0:20           ` Robert Hancock
2007-02-28  1:32             ` Hiro Yoshioka

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