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From: Hiro Yoshioka <hyoshiok@miraclelinux.com> To: riel@redhat.com Cc: davej@redhat.com, harlan@artselect.com, nickpiggin@yahoo.com.au, l_allegrucci@yahoo.it, linux-kernel@vger.kernel.org, mingo@elte.hu, suparna@in.ibm.com, jens.axboe@oracle.com, hyoshiok@miraclelinux.com Subject: Re: SMP performance degradation with sysbench Date: Tue, 27 Feb 2007 13:03:05 +0900 (JST) [thread overview] Message-ID: <20070227.130305.424251739.hyoshiok@miraclelinux.com> (raw) In-Reply-To: <45E37EA3.3060101@redhat.com> Hi, From: Rik van Riel <riel@redhat.com> > Hiro Yoshioka wrote: > > Howdy, > > > > MySQL 5.0.26 had some scalability issues and it solved since 5.0.32 > > http://ossipedia.ipa.go.jp/capacity/EV0612260303/ > > (written in Japanese but you may read the graph. We compared > > 5.0.24 vs 5.0.32) snip > > MySQL tries to get a mutex but it spends about 16.8% of CPU on 8 core > > machine. > > > > I think there are a lot of room to be inproved in MySQL implementation. > > That's one aspect. > > The other aspect of the problem is that when the number of > threads exceeds the number of CPU cores, Linux no longer > manages to keep the CPUs busy and we get a lot of idle time. > > On the other hand, with the number of threads being equal to > the number of CPU cores, we are 100% CPU bound... I have a question. If so, what is the difference of kernel's view between SMP and CPU cores? 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? Regards, Hiro -- Hiro Yoshioka CTO/Miracle Linux Corporation http://blog.miraclelinux.com/yume/
next prev parent reply other threads:[~2007-02-27 4:27 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 [this message] 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 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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