From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754142Ab1A0Xl4 (ORCPT ); Thu, 27 Jan 2011 18:41:56 -0500 Received: from ipmail06.adl2.internode.on.net ([150.101.137.129]:38974 "EHLO ipmail06.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753654Ab1A0Xlz (ORCPT ); Thu, 27 Jan 2011 18:41:55 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AtAEAAOPQU15LN5mgWdsb2JhbACkfBYBARYiJIgrtDsNhUIE Date: Fri, 28 Jan 2011 10:41:52 +1100 From: Dave Chinner To: Mark Lord Cc: Stan Hoeppner , Christoph Hellwig , Alex Elder , Linux Kernel , xfs@oss.sgi.com Subject: Re: xfs: very slow after mount, very slow at umount Message-ID: <20110127234152.GN21311@dastard> References: <4D40C8D1.8090202@teksavvy.com> <20110127033011.GH21311@dastard> <4D40EB2F.2050809@teksavvy.com> <4D418B57.1000501@teksavvy.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4D418B57.1000501@teksavvy.com> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jan 27, 2011 at 10:12:23AM -0500, Mark Lord wrote: > On 11-01-27 12:30 AM, Stan Hoeppner wrote: > > Mark Lord put forth on 1/26/2011 9:49 PM: > > > >> agcount=7453 > > > > That's probably a bit high Mark, and very possibly the cause of your problems. > > :) Unless the disk array backing this filesystem has something like 400-800 > > striped disk drives. You said it's a single 2TB drive right? > > > > The default agcount for a single drive filesystem is 4 allocation groups. For > > mdraid (of any number of disks/configuration) it's 16 allocation groups. > > > > Why/how did you end up with 7452 allocation groups? That can definitely cause > > some performance issues due to massively excessive head seeking, and possibly > > all manner of weirdness. > > This is great info, exactly the kind of feedback I was hoping for! > > The filesystem is about a year old now, and I probably used agsize=nnnnn > when creating it or something. > > So if this resulted in what you consider to be many MANY too MANY ags, > then I can imagine the first new file write wanting to go out and read > in all of the ag data to determine the "best fit" or something. > Which might explain some of the delay. > > Once I get the new 2TB drive, I'll re-run mkfs.xfs and then copy everything > over onto a fresh xfs filesystem. > > Can you recommend a good set of mkfs.xfs parameters to suit the characteristics > of this system? http://xfs.org/index.php/XFS_FAQ#Q:_I_want_to_tune_my_XFS_filesystems_for_.3Csomething.3E And perhaps you want to consider the allocsize mount option, though that shouldn't be necessary for 2.6.38+... Cheers, Dave. -- Dave Chinner david@fromorbit.com