From: Chuck Lever Subject: Re: [PATCH 2/3] NFS: Add NFS_MOUNT_NONEGDE flag to avoid caching negative dentries Date: Fri, 18 Jan 2008 16:12:51 -0500 Message-ID: <16A4251B-73DA-4F2B-BA86-6A5890CC727B@oracle.com> References: <20080115163013.GC18911@newbie.thebellsplace.net> <1200415972.7702.7.camel@heimdal.trondhjem.org> <20080116012209.GB26010@newbie.thebellsplace.net> <1200451350.28088.43.camel@heimdal.trondhjem.org> <478DFD5A.1040501@RedHat.com> <01AE8AF878612047A442668306EAEB05018178E7@SACEXMV01.hq.netapp.com> <1200516219.6932.22.camel@heimdal.trondhjem.org> <20080118152902.GF7128@newbie.thebellsplace.net> Mime-Version: 1.0 (Apple Message framework v753) Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Cc: Trond Myklebust , "Muntz, Daniel" , Steve Dickson , NFS list To: Bob Bell Return-path: Received: from rgminet01.oracle.com ([148.87.113.118]:38137 "EHLO rgminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760029AbYARVN4 (ORCPT ); Fri, 18 Jan 2008 16:13:56 -0500 In-Reply-To: <20080118152902.GF7128-y89O8yXFYpDSsb2jM9SCN5/hYUUxywnI@public.gmane.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: Hi Bob- On Jan 18, 2008, at 10:29 AM, Bob Bell wrote: > On Wed, Jan 16, 2008 at 03:49:20PM -0500, Chuck Lever wrote: >> On Jan 16, 2008, at 3:43 PM, Trond Myklebust wrote: >>> How about >>> -odircache=aggr[essive] /* Full caching */ >>> -odircache=noneg[ative] /* Positive lookups only */ >>> -odircache=off /* strict lookup revalidation */ >> >> "-olookupcache=" would be even more specific, if not more >> verbose. dircache=off implies that not even readdir results are >> cached. >> >> -olookupcache=full >> -olookupcache=pos[itive] >> -olookupcache=strict > > I think that "lookupcache" is a little more accurate, and perhaps > worth the verbosity. "dircache" could be misinterpreted to imply > that directory listings are being cached -- which, incidentally, > I'm start to receive complaints is a problem for us, too... > > Converstation on this seems to have died down, and I'm ready to > revisit the patch. I'm inclined to go with: > -o lookupcache=full > -o lookupcache=pos[itive] > -o lookupcache=none > > If you have a strong (enough) opinion otherwise, please speak up > now and save me the trouble of an extra pass at the patch... I understand that lookupcache=full would be current behavior, and =positive would prevent caching negative dentries. When would anyone want to use lookupcache=none -- what exactly would it do? How is it different than actimeo=0? -- Chuck Lever chuck[dot]lever[at]oracle[dot]com