From: Trond Myklebust Subject: Re: [PATCH 0/3] Intro: Better handling coarse-grained timestamps Date: Wed, 16 Jan 2008 14:47:52 -0500 Message-ID: <1200512872.6932.8.camel@heimdal.trondhjem.org> References: <20080115162658.GA18911@newbie.thebellsplace.net> <20080116015526.GC26010@newbie.thebellsplace.net> <1200449912.28088.22.camel@heimdal.trondhjem.org> Mime-Version: 1.0 Content-Type: text/plain Cc: Bob Bell , linux-nfs@vger.kernel.org To: "david m. richter" Return-path: Received: from pat.uio.no ([129.240.10.15]:42593 "EHLO pat.uio.no" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751598AbYAPTr5 (ORCPT ); Wed, 16 Jan 2008 14:47:57 -0500 In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, 2008-01-16 at 12:16 -0500, david m. richter wrote: > so then, would it instead be correct to say that the negative > dentry caching on the client afforded by the delegation is beneficial > insofar as it obviates the client's need to revalidate the file/directory > in question? if so, i understand the flawed CTO wording and will fix the > wiki. Delegations give you a guarantee that the directory contents (i.e. the readdir() information) have not changed, and so the client no longer needs to poll the directory for change information. IOW: specifically they allow the client to optimise away the GETATTR call in opendir(), and they allow it to optimise away most of nfs_lookup_revalidate(). Cheers Trond