From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Mon, 06 Oct 2008 15:32:21 -0700 (PDT) Received: from cuda.sgi.com (cuda3.sgi.com [192.48.176.15]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with ESMTP id m96MWIrU029200 for ; Mon, 6 Oct 2008 15:32:19 -0700 Received: from ipmail05.adl2.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 0BDDA13A26A9 for ; Mon, 6 Oct 2008 15:33:56 -0700 (PDT) Received: from ipmail05.adl2.internode.on.net (ipmail05.adl2.internode.on.net [203.16.214.145]) by cuda.sgi.com with ESMTP id sajCAbB5ese1Jg6G for ; Mon, 06 Oct 2008 15:33:56 -0700 (PDT) Date: Tue, 7 Oct 2008 09:31:41 +1100 From: Dave Chinner Subject: Re: XFS: "slow at directory traversal .. after 3 years of use" Message-ID: <20081006223141.GS30001@disturbed> References: <1c08324d0810061325kdd1453alb9eab9ceb769b1cf@mail.gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Justin Piszcz Cc: xfs@oss.sgi.com, Lennart Hansen On Mon, Oct 06, 2008 at 04:30:22PM -0400, Justin Piszcz wrote: > Someone pointed me to the following paper: > > http://www.stdlib.net/~colmmacc/Apachecon-EU2005/scaling-apache-handout.pdf > > Which states: > > After nearly 3 years of use, some problems with XFS became > noticeable. As the number of used inodes in the filesystem grows > XFS becomes very slow at directory traversal. Although this did > not impede web-serving it did have a heavy impact on how quickly > we could synchronise content with the primary sources. There's no detail of what the problem was, just that it slowed down. Could have been many things, and one of the possibilities was the in-core XFS inode hash scalability problems (that you could work around with an ihashsize=XXX mount option).... > Dave / Eric, comments here? Does ext3 suffer from the same > problem? An ext3 filesystem being faster than a 3 year old production XFS filesystem - no surprise there as the XFS directories were probably fragmented. After three years of continual use, I'd be extremely surprised if the ext3 H-tree directory structures perform anywhere near as well as XFS as the fragmentation characteristics of ext3 directories are far worse than XFS and ext3 does not have directory readahead like XFS does. An example - kernel.org moved from ext3 to XFS primarily because the directory performance of XFS is better than ext3 on these sorts of workloads.... > Have these issues been fixed since 2005? Would inode64 alleviate > some of these problems? Well, the incore inode hashes have no problems now they have been converted to radix trees. Witout any further detail of what the problem was, I can't really say anything else.... Barry - sounds like you need to make xfs_fsr defrag directories. ;) Cheers, Dave. -- Dave Chinner david@fromorbit.com