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From: Lorenzo Allegrucci <l_allegrucci@yahoo.it>
To: Rik van Riel <riel@redhat.com>
Cc: "\"J.A. Magallón\"" <jamagallon@ono.com>,
	"Hiro Yoshioka" <hyoshiok@miraclelinux.com>,
	davej@redhat.com, harlan@artselect.com, nickpiggin@yahoo.com.au,
	linux-kernel@vger.kernel.org, mingo@elte.hu, suparna@in.ibm.com,
	jens.axboe@oracle.com
Subject: Re: SMP performance degradation with sysbench
Date: Tue, 27 Feb 2007 20:05:27 +0100	[thread overview]
Message-ID: <1172603127.5482.35.camel@odyssey.lan> (raw)
In-Reply-To: <45E439E4.5030703@redhat.com>

On Tue, 2007-02-27 at 09:02 -0500, Rik van Riel wrote:
> J.A. Magallón wrote:
> > On Mon, 26 Feb 2007 23:31:29 -0500, Rik van Riel <riel@redhat.com> wrote:
> > 
> >> Hiro Yoshioka wrote:
> 
> >>> Another question. When the number of threads exceeds the number of
> >>> CPU cores, we may get a lot of idle time. Then a workaround of
> >>> MySQL is that do not creat threads which exceeds the number
> >>> of CPU cores. Is it right?
> >> Not really, that would make it impossible for MySQL to
> >> handle more simultaneous database queries than the system
> >> has CPUs.
> >>
> > 
> > I don't know myqsl internals, but you assume one thread per query.
> > If its more like Apache, one long living thread for several connections ?
> 
> Yes, they are longer lived client connections.  One thread
> per connection, just like Apache.
> 
> > Its the same to answer 4+4 queries than 8 at half the speed, isn't it ?
> 
> That still doesn't fix the potential Linux problem that this
> benchmark identified.
> 
> To clarify: I don't care as much about MySQL performance as
> I care about identifying and fixing this potential bug in
> Linux.

Here http://people.freebsd.org/~kris/scaling/mysql.html Kris Kennaway
talks about a patch for FreeBSD 7 which addresses poor scalability
of file descriptor locking and that it's responsible for almost all
of the performance and scaling improvements.


Chiacchiera con i tuoi amici in tempo reale! 
 http://it.yahoo.com/mail_it/foot/*http://it.messenger.yahoo.com 

  parent reply	other threads:[~2007-02-27 19:05 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-25 17:44 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 [this message]
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
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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