From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [MMTests] IO metadata on XFS Date: Mon, 2 Jul 2012 02:32:26 -0400 Message-ID: <20120702063226.GA32151@infradead.org> References: <20120620113252.GE4011@suse.de> <20120629111932.GA14154@suse.de> <20120629112505.GF14154@suse.de> <20120701235458.GM19223@dastard> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Mel Gorman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com To: Dave Chinner Return-path: Content-Disposition: inline In-Reply-To: <20120701235458.GM19223@dastard> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Mon, Jul 02, 2012 at 09:54:58AM +1000, Dave Chinner wrote: > That will be caused by the fact we changed all the metadata updates > to be logged, which means a transaction every time .dirty_inode is > called. > > This should mostly go away when XFS is converted to use .update_time > rather than .dirty_inode to only issue transactions when the VFS > updates the atime rather than every .dirty_inode call... I think the patch to do that conversion still needs review.. > It increases the CPU overhead (dirty_inode can be called up to 4 > times per write(2) call, IIRC), so with limited numbers of > threads/limited CPU power it will result in lower performance. Where > you have lots of CPU power, there will be little difference in > performance... When I checked it it could only be called twice, and we'd already optimize away the second call. I'd defintively like to track down where the performance changes happend, at least to a major version but even better to a -rc or git commit. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org