From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Mon, 17 Dec 2007 20:10:58 -0800 (PST) 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 lBI4AkZm019629 for ; Mon, 17 Dec 2007 20:10:49 -0800 Message-ID: <47674892.9070506@sgi.com> Date: Tue, 18 Dec 2007 15:12:02 +1100 From: Lachlan McIlroy Reply-To: lachlan@sgi.com MIME-Version: 1.0 Subject: Re: [review] Remove the xfs refcache References: <4765EC66.5020202@sgi.com> <4765F444.8010705@sgi.com> <20071217071426.GA11462@infradead.org> In-Reply-To: <20071217071426.GA11462@infradead.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Christoph Hellwig Cc: Donald Douwsma , xfs-oss , gnb@sgi.com Christoph Hellwig wrote: > On Mon, Dec 17, 2007 at 03:00:04PM +1100, Lachlan McIlroy wrote: >> Hey hold on there buddy! We may need to reactivate this code to fix some >> performance issues. I've acttually got this code working and proven that >> it is one way to fix some of the NAS/NFS issues we have. >> >> The little comment that reads "reference cache not needed for NFS in 2.6" >> is wrong - we do need it or something like it. > > Not in XFS, though. This thing needs to be done genericly in NFSD. > Greg has been working on an open files cache in nfsd which should be > helping this. > > Adding a cache like this back into XFS will get my veto (at least for > mainline where I have a bit of a say :)) > Greg's NFS OFC will provide better performance for strictly NFS workloads and if all we are trying to fix here is the NFS issues then I agree with you that the OFC should not go into XFS. Since I have been able to reproduce some of our NAS/NFS performance problems without NFS (that is demonstrate that the problems are in XFS) it makes some sense to fix these in XFS. I have observed that for some non-NFS workloads we see a significant reduction in log traffic with the OFC in XFS so for reasons beyond NFS there may be a need to reactivate the refcache code. For the moment we are still analysing the pros/cons.