From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Sandeen Subject: Re: ext4 unlink performance Date: Sat, 15 Nov 2008 17:08:09 -0600 Message-ID: <491F5659.7010206@redhat.com> References: <20081113185712.GB11204@untroubled.org> <20081113191000.GA11516@untroubled.org> <20081113204240.GF21652@mit.edu> <20081114041121.GB11746@untroubled.org> <20081114145914.GE25117@mit.edu> <20081115204423.GA4671@untroubled.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: linux-ext4@vger.kernel.org Return-path: Received: from mx2.redhat.com ([66.187.237.31]:57326 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751815AbYKOXIO (ORCPT ); Sat, 15 Nov 2008 18:08:14 -0500 Received: from int-mx2.corp.redhat.com (int-mx2.corp.redhat.com [172.16.27.26]) by mx2.redhat.com (8.13.8/8.13.8) with ESMTP id mAFN8BTJ003228 for ; Sat, 15 Nov 2008 18:08:11 -0500 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx2.corp.redhat.com (8.13.1/8.13.1) with ESMTP id mAFN8BIg003286 for ; Sat, 15 Nov 2008 18:08:11 -0500 Received: from liberator.sandeen.net (sebastian-int.corp.redhat.com [172.16.52.221]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id mAFN89Ad015736 for ; Sat, 15 Nov 2008 18:08:10 -0500 In-Reply-To: <20081115204423.GA4671@untroubled.org> Sender: linux-ext4-owner@vger.kernel.org List-ID: Bruce Guenter wrote: > On Fri, Nov 14, 2008 at 09:59:14AM -0500, Theodore Tso wrote: >> This is beginning to perhaps sound like a layout problem of some kind. > > To test this theory, I ran one test where I populated the filesystem > with ext3 and then mounted as ext4 to do the unlinking. This produced > unlink times comparable with ext3. That is, the degredation is occuring > when the filesystem is populated, not when it is cleaned. Maybe run the unlinking activity through seekwatcher* in both cases, to see where the IO is happening. (also, you're right w.r.t. lvm/dm; barriers don't pass and should get disabled after the first attempt at a barrier write). -Eric *http://oss.oracle.com/~mason/seekwatcher/ (also packaged for fedora, maybe other distros as well)