Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750735AbXB1Ba2 (ORCPT ); Tue, 27 Feb 2007 20:30:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750809AbXB1Ba2 (ORCPT ); Tue, 27 Feb 2007 20:30:28 -0500 Received: from ns.miraclelinux.com ([219.118.163.66]:40512 "EHLO mail01.miraclelinux.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750735AbXB1Ba1 (ORCPT ); Tue, 27 Feb 2007 20:30:27 -0500 Date: Wed, 28 Feb 2007 10:32:39 +0900 (JST) Message-Id: <20070228.103239.846946216.hyoshiok@miraclelinux.com> To: hancockr@shaw.ca Cc: davej@redhat.com, harlan@artselect.com, nickpiggin@yahoo.com.au, riel@redhat.com, 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 From: Hiro Yoshioka In-Reply-To: <45E4CAC9.4070504@shaw.ca> References: <45E4CAC9.4070504@shaw.ca> X-Mailer: Mew version 3.3 on XEmacs 21.4.13 (Rational FORTRAN) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1670 Lines: 43 From: Robert Hancock Subject: Re: SMP performance degradation with sysbench Date: Tue, 27 Feb 2007 18:20:25 -0600 Message-ID: <45E4CAC9.4070504@shaw.ca> > 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) > > > > The following is oprofile data > > ==> > > cpu=8-mysql=5.0.32-gcc=3.4/oprofile-eu=2200-op=default-none/opreport-l.txt > > <== > > CPU: Core Solo / Duo, speed 2666.76 MHz (estimated) > > Counted CPU_CLK_UNHALTED events (Unhalted clock cycles) with a unit > > mask of 0x00 (Unhalted core cycles) count 100000 > > samples % app name symbol name > > 47097502 16.8391 libpthread-2.3.4.so pthread_mutex_trylock > > 19636300 7.0207 libpthread-2.3.4.so pthread_mutex_unlock > > 18600010 6.6502 mysqld rec_get_offsets_func > > 18121328 6.4790 mysqld btr_search_guess_on_hash > > 11453095 4.0949 mysqld row_search_for_mysql > > > > MySQL tries to get a mutex but it spends about 16.8% of CPU on 8 core > > machine. > > Curious that it calls pthread_mutex_trylock (as opposed to > pthread_mutex_lock) so often. Maybe they're doing some kind of mutex > lock busy-looping? Yes, it is. Regards, Hiro - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/