From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753872Ab1A0DxU (ORCPT ); Wed, 26 Jan 2011 22:53:20 -0500 Received: from ironport2-out.teksavvy.com ([206.248.154.181]:6893 "EHLO ironport2-out.pppoe.ca" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753367Ab1A0DxT (ORCPT ); Wed, 26 Jan 2011 22:53:19 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApIBAOp6QE1Ld/sX/2dsb2JhbAAMhAjMc5BogSODOHQEhRg X-IronPort-AV: E=Sophos;i="4.60,384,1291611600"; d="scan'208";a="89378518" Message-ID: <4D40EC2D.5020507@teksavvy.com> Date: Wed, 26 Jan 2011 22:53:17 -0500 From: Mark Lord User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-GB; rv:1.9.2.13) Gecko/20101207 Thunderbird/3.1.7 MIME-Version: 1.0 To: Dave Chinner CC: Christoph Hellwig , Alex Elder , Linux Kernel , xfs@oss.sgi.com Subject: Re: xfs: very slow after mount, very slow at umount References: <4D40C8D1.8090202@teksavvy.com> <4D40CDCF.4010301@teksavvy.com> <20110127034314.GI21311@dastard> In-Reply-To: <20110127034314.GI21311@dastard> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11-01-26 10:43 PM, Dave Chinner wrote: > On Wed, Jan 26, 2011 at 08:43:43PM -0500, Mark Lord wrote: >> On 11-01-26 08:22 PM, Mark Lord wrote: .. >> Thinking about it some more: the first problem very much appears as if >> it is due to a filesystem check happening on the already-mounted filesystem, >> if that makes any kind of sense (?). > > Not to me. You can check this simply by looking at the output of > top while the problem is occurring... Top doesn't show anything interesting, since disk I/O uses practically zero CPU. >> running xfs_check on the umounted drive takes about the same 30-60 seconds, >> with the disk activity light fully "on". > > Well, yeah - XFS check reads all the metadata in the filesystem, so > of course it's going to thrash your disk when it is run. The fact it > takes the same length of time as whatever problem you are having is > likely to be coincidental. I find it interesting that the mount takes zero-time, as if it never actually reads much from the filesystem. Something has to eventually read the metadata etc. >> The other thought that came to mind: this behaviour has only been >> noticed recently, probably because I have recently added about >> 1000 new files (hundreds of MB each) to the videos/ directory on >> that filesystem. Whereas before, it had fewer than 500 (multi-GB) >> files in total. >> >> So if it really is doing some kind of internal filesystem check, >> then the time required has only recently become 3X larger than >> before.. so the behaviour may not be new/recent, but now is very >> noticeable. > > Where does that 3x figure come from? Well, it used to have about 500 files/subdirs on it, and now it has somewhat over 1500 files/subdirs. That's a ballpark estimate of 3X the amount of meta data. All of these files are at least large (hundreds of MB), and a lot are huge (many GB) in size. Cheers