From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750910AbXB0OC5 (ORCPT ); Tue, 27 Feb 2007 09:02:57 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750911AbXB0OC5 (ORCPT ); Tue, 27 Feb 2007 09:02:57 -0500 Received: from mx1.redhat.com ([66.187.233.31]:37568 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750897AbXB0OC4 (ORCPT ); Tue, 27 Feb 2007 09:02:56 -0500 Message-ID: <45E439E4.5030703@redhat.com> Date: Tue, 27 Feb 2007 09:02:12 -0500 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 1.5.0.7 (X11/20061008) MIME-Version: 1.0 To: =?UTF-8?B?IkouQS4gTWFnYWxsw7NuIg==?= CC: Hiro Yoshioka , 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 Subject: Re: SMP performance degradation with sysbench References: <20070226223645.GA24174@redhat.com> <98df96d30702261632u7479c9b2sce93f80f68bbc8d0@mail.gmail.com> <45E37EA3.3060101@redhat.com> <20070227.130305.424251739.hyoshiok@miraclelinux.com> <45E3B421.603@redhat.com> <20070227091409.6f3d12f9@werewolf-wl> In-Reply-To: <20070227091409.6f3d12f9@werewolf-wl> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org J.A. Magallón wrote: > On Mon, 26 Feb 2007 23:31:29 -0500, Rik van Riel 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. -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic.