From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753215AbXCMKiA (ORCPT ); Tue, 13 Mar 2007 06:38:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752599AbXCMKiA (ORCPT ); Tue, 13 Mar 2007 06:38:00 -0400 Received: from smtp108.plus.mail.mud.yahoo.com ([68.142.206.241]:45786 "HELO smtp108.plus.mail.mud.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753217AbXCMKh7 (ORCPT ); Tue, 13 Mar 2007 06:37:59 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=s1024; d=yahoo.com.au; h=Received:X-YMail-OSG:Message-ID:Date:From:User-Agent:X-Accept-Language:MIME-Version:To:CC:Subject:References:In-Reply-To:Content-Type:Content-Transfer-Encoding; b=X7Cv+3micT7BhK19/U2SCLko9RysjPm+Z+ZppTcrVhNsZTCvHJ8yeLjhc6y7WvTR+pswTzE+CaN9/2zynkhBmrL/yHqKblef33emlSZS8G/HXBBU/AbcdiMld+xfIPiHufhW8PoD0HXG5VIrIAcXpNwcU7BhEhvFhe2ZAv09f9w= ; X-YMail-OSG: zx7G8CcVM1mZ1R4PrMNd6RaqWg.Os9s8yPtsJYyJDz0Tyh349yfXXcHDQazFgTT.3bz33mxf4iMHEuDc7uSxEWWXrESvm.A5BoQw_lKdXfFBLy9YSpaKnA-- Message-ID: <45F67F02.5020401@yahoo.com.au> Date: Tue, 13 Mar 2007 21:37:54 +1100 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12) Gecko/20051007 Debian/1.7.12-1 X-Accept-Language: en MIME-Version: 1.0 To: Andrea Arcangeli CC: Anton Blanchard , Rik van Riel , Lorenzo Allegrucci , linux-kernel@vger.kernel.org, Ingo Molnar , Suparna Bhattacharya , Jens Axboe Subject: Re: SMP performance degradation with sysbench References: <1172425476.5489.11.camel@odyssey.lan> <45E21FEC.9060605@redhat.com> <45E2E244.8040009@yahoo.com.au> <20070312220042.GA807@kryten> <45F63266.1080509@yahoo.com.au> <20070313094559.GC8992@v2.random> <45F67796.4040508@yahoo.com.au> <20070313103134.GF8992@v2.random> In-Reply-To: <20070313103134.GF8992@v2.random> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrea Arcangeli wrote: > On Tue, Mar 13, 2007 at 09:06:14PM +1100, Nick Piggin wrote: > >>Well ignoring the HT issue, I was seeing lots of idle time simply >>because userspace could not keep up enough load to the scheduler. >>There simply were fewer runnable tasks than CPU cores. > > > When you said idle I thought idle and not waiting for I/O. Waiting for > I/O would be hardly a kernel issue ;). If they're not waiting for I/O > and they're not scheduling in userland with nanosleep/pause, the cpu > shouldn't go idle. Even if they're calling sched_yield in a loop the > cpu should account for zero idle time as far as I can tell. Well it wasn't iowait time. From Anton's analysis, I would probably say it was time waiting for either the glibc malloc mutex or MySQL heap mutex. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com