From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Chinner Subject: Re: [PATCH 12/17] fs: Introduce per-bucket inode hash locks Date: Thu, 30 Sep 2010 12:43:31 +1000 Message-ID: <20100930024331.GW5665@dastard> References: <1285762729-17928-1-git-send-email-david@fromorbit.com> <1285762729-17928-13-git-send-email-david@fromorbit.com> <20100930015213.GA1535@infradead.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org To: Christoph Hellwig Return-path: Received: from bld-mail14.adl6.internode.on.net ([150.101.137.99]:34595 "EHLO mail.internode.on.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752452Ab0I3Cng (ORCPT ); Wed, 29 Sep 2010 22:43:36 -0400 Content-Disposition: inline In-Reply-To: <20100930015213.GA1535@infradead.org> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Wed, Sep 29, 2010 at 09:52:14PM -0400, Christoph Hellwig wrote: > > Instead of doing the lock overkill on a still fundamentally global data > structure what about replacing this with something better. I know > you've already done this with the XFS icache, and while the per-AG > concept obviously can't be generic at least some of the lessons could be > applied. The XFS inode cache design is tied tightly to the inode layout in XFS, so the tree-per-ag-per-mount parallelism design really does not work in a generic manner. Sure, we could probably make it a hashed-tree rather than hashed-link-list design, but that's a much more fundamental change than just splitting the locks up. > then again how much testing did this get anyway given that you > benchmark ran mostly XFS which doesn't hit this at all? I've been running comparitive benchmarks on ext4 as well so that I also test all the generic paths. > If it was up to me I'd dtop this (and the bl_list addition) from the > series for now and wait for people who care about the scalability of > the generic icache code to come up with a better data structure. I think that it's going to take a lot of work to come up with something more generically optimal, so in the mean time I think this is a net win for filesystems that use the generic icache. Cheers, Dave. -- Dave Chinner david@fromorbit.com