From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Wed, 09 Apr 2008 16:01:56 -0700 (PDT) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with SMTP id m39N1jX5010763 for ; Wed, 9 Apr 2008 16:01:48 -0700 Date: Thu, 10 Apr 2008 09:02:19 +1000 From: David Chinner Subject: Re: [patch] Re: Does XFS prevent disk spindown? Message-ID: <20080409230219.GM108924158@sgi.com> References: <20080401003005.GJ103491721@sgi.com> <47F1CF6D.2040103@sandeen.net> <47F9735E.8020900@sgi.com> <20080407215855.GE108924158@sgi.com> <20080409041113.GC108924158@sgi.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: Thor Kristoffersen Cc: David Chinner , Timothy Shimmin , xfs@oss.sgi.com On Wed, Apr 09, 2008 at 11:32:34PM +0200, Thor Kristoffersen wrote: > David Chinner writes: > >> = sectsz=512 sunit=0 blks, lazy-count=1 > >> realtime =none extsz=4096 blocks=0, rtextents=0 > >> > >> Is that what's causing it? I have never specified any lazy-count option > >> when I created or mounted the filesystem. I didn't even know it existed. > > > > Introduced in 2.6.22, and recently was made the default mkfs config. > > > > Try the patch below. > > Thanks a lot, David! Your patch worked perfectly. Also thanks to the > others who helped me track down this issue. Cool. I'll get that patch reviewed and checked in, then. > BTW, what are the consequences of setting lazy-count to 0? Less safety? > Reduced performance? One a single disk? No difference to performance, but significantly lower latency on metadata operations is seen when using lazy-count=1. If you have lots of disks, or low-latency caches in front of your disks, lazy-count=1 will prevent superblock updates from being the metadata performance limiting factor. Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group