From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id o2D0EucX038641 for ; Fri, 12 Mar 2010 18:14:57 -0600 Received: from mail.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 2F4F32387B9 for ; Fri, 12 Mar 2010 16:16:29 -0800 (PST) Received: from mail.internode.on.net (bld-mail19.adl2.internode.on.net [150.101.137.104]) by cuda.sgi.com with ESMTP id 9EoFyZHgTjGgCsKm for ; Fri, 12 Mar 2010 16:16:29 -0800 (PST) Date: Sat, 13 Mar 2010 11:16:26 +1100 From: Dave Chinner Subject: Re: XFS buffered sequential read performance low after kernel upgrade Message-ID: <20100313001626.GE4732@dastard> References: <4B9A2A00.1050304@hardwarefreak.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4B9A2A00.1050304@hardwarefreak.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Stan Hoeppner Cc: xfs@oss.sgi.com On Fri, Mar 12, 2010 at 05:48:16AM -0600, Stan Hoeppner wrote: > Hello, > > I'm uncertain whether this is the best place to bring this up. I've been > lurking a short while and it seems almost all posts here deal with dev > issues. On the off chance this is an appropriate forum, here goes. .... > hdparm test results for the filesystems: > > /dev/sda2: > Timing O_DIRECT disk reads: 236 MB in 3.01 seconds = 78.48 MB/sec > /dev/sda2: > Timing buffered disk reads: 172 MB in 3.03 seconds = 56.68 MB/sec > > /dev/sda6: > Timing O_DIRECT disk reads: 238 MB in 3.00 seconds = 79.21 MB/sec > /dev/sda6: > Timing buffered disk reads: 116 MB in 3.03 seconds = 38.27 MB/sec > > /dev/sda7: > Timing O_DIRECT disk reads: 238 MB in 3.01 seconds = 79.10 MB/sec > /dev/sda7: > Timing buffered disk reads: 114 MB in 3.00 seconds = 37.99 MB/sec Those tests don't go through the filesystem - they go directly to the block device. Hence if these are different to your old kernel, the problem is outside XFS. I'd suggest the most likely cause is the elevator - if you are using CFQ try turning off the new low-latency mode, or changing to deadline or noop and see if the problem goes away. Also, the XFS partitions are on the inner edge of the disk, so they are always going to be slower (can be as low as half the speed) than partitions on the outer edge of the disk for sequential access... Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs