From: Andreas Dilger Subject: Re: [Bug 14830] When other IO is running sync times go to 10 to 20 minutes Date: Wed, 27 Jan 2010 12:43:57 -0700 Message-ID: <6465E5ED-8392-4929-9FD6-EFCCA7D75E0B@sun.com> References: <201001251119.o0PBJDXw012169@demeter.kernel.org> <20100127130625.GQ7517@skl-net.de> Mime-Version: 1.0 Content-Type: text/plain; CHARSET=US-ASCII; delsp=yes; format=flowed Content-Transfer-Encoding: 7BIT Cc: Michael Godfrey , linux-ext4@vger.kernel.org To: Andre Noll Return-path: Received: from sca-es-mail-2.Sun.COM ([192.18.43.133]:40457 "EHLO sca-es-mail-2.sun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753283Ab0A0ToF (ORCPT ); Wed, 27 Jan 2010 14:44:05 -0500 Received: from fe-sfbay-09.sun.com ([192.18.43.129]) by sca-es-mail-2.sun.com (8.13.7+Sun/8.12.9) with ESMTP id o0RJhxAv021550 for ; Wed, 27 Jan 2010 11:44:01 -0800 (PST) Received: from conversion-daemon.fe-sfbay-09.sun.com by fe-sfbay-09.sun.com (Sun Java(tm) System Messaging Server 7u2-7.04 64bit (built Jul 2 2009)) id <0KWX00H008432I00@fe-sfbay-09.sun.com> for linux-ext4@vger.kernel.org; Wed, 27 Jan 2010 11:43:59 -0800 (PST) In-reply-to: <20100127130625.GQ7517@skl-net.de> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 2010-01-27, at 06:06, Andre Noll wrote: > On 11:19, bugzilla-daemon@bugzilla.kernel.org wrote: >> After kill -9 of the sync run it took about 20 minutes before >> it died. > > I was seeing similar behaviour on one of our servers, and changing > the io scheduler to noop fixed things for me. So it seems to be an > issue with cfq which is somehow triggered by ext4 but not by ext3. > > To change the IO scheduler, just execute > > echo noop > /sys/block/sda/queue/scheduler Andre, could you please also test deadline instead of noop? In general, deadline has nearly the same IO behaviour as noop, but still allows simple request merging and is generally a better option than noop. Cheers, Andreas -- Andreas Dilger Sr. Staff Engineer, Lustre Group Sun Microsystems of Canada, Inc.