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 q5Q2KHqN046230 for ; Mon, 25 Jun 2012 21:20:18 -0500 Received: from ipmail04.adl6.internode.on.net (ipmail04.adl6.internode.on.net [150.101.137.141]) by cuda.sgi.com with ESMTP id wRNdCeFjoP9woT3p for ; Mon, 25 Jun 2012 19:20:15 -0700 (PDT) Date: Tue, 26 Jun 2012 12:20:11 +1000 From: Dave Chinner Subject: Re: [regression] stack overflow in xfs_buf_iodone_callbacks Message-ID: <20120626022011.GB19223@dastard> References: <20120621091803.GB10673@dastard> <20120621163409.GA7897@infradead.org> <20120621232414.GD10673@dastard> <20120622164147.GA20617@infradead.org> <20120622233955.GY19223@dastard> <20120625090657.GA22726@infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20120625090657.GA22726@infradead.org> 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: Christoph Hellwig Cc: xfs@oss.sgi.com On Mon, Jun 25, 2012 at 05:06:58AM -0400, Christoph Hellwig wrote: > On Sat, Jun 23, 2012 at 09:39:55AM +1000, Dave Chinner wrote: > > Hmmmm. How often do we get real io completion occurring before we > > call _xfs_buf_ioend() here? I can't see that it is common, so this > > is probably fine, but perhaps a few numbers might help here? If it > > is rare as we think it is, then yeah, that would work.... > > The only case where I can see it ever hapen is when sending tons > of separate I/Os in one go to a reall fast device, e.g. a very > fragmented large directory to superfast battery backed dram device. > > And even then I don't think it matters very much - for reads we > generally do not have an b_iodone handler attached, so for these > the change does not make any different. We will very soon - CRC checks after reading for disk will be done after reads. The patch series I'm working on at the moment introduces sanity checks of buffers on read completion - it doesn't do CRC checks yet, but it moves all the checks we do on read completion into iodone callbacks, and when CRCs are introduced they will simply be slotted into those functions.... > For delayed writes the > additional context switch also doesn't have a major impact on > performance, so the only thing where we could see a difference > is synchronous writes, of which we don't have a lot left, and > essentially none unless the shrinkers kick in and need to do > synchronous reclaims. *nod* Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs