From: "Roy M." Subject: Re: Is NFS v4 stable and recommend to use now? Date: Sat, 4 Oct 2008 21:34:49 +0800 Message-ID: References: <20081002171719.GA30408@fieldses.org> <20081003215247.GJ19057@fieldses.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: linux-nfs@vger.kernel.org To: "J. Bruce Fields" Return-path: Received: from rv-out-0506.google.com ([209.85.198.227]:62431 "EHLO rv-out-0506.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751087AbYJDNey (ORCPT ); Sat, 4 Oct 2008 09:34:54 -0400 Received: by rv-out-0506.google.com with SMTP id k40so2122374rvb.1 for ; Sat, 04 Oct 2008 06:34:49 -0700 (PDT) In-Reply-To: <20081003215247.GJ19057@fieldses.org> Sender: linux-nfs-owner@vger.kernel.org List-ID: Hello, On Sat, Oct 4, 2008 at 5:52 AM, J. Bruce Fields wrote: > I doubt the pattern of I/O really matters much--it's the opens and > closes themselves that matter. > > (In v3, close-to-open cache consistency requires that the client always > fetch file attributes from the server on an open. That means open() is > always going to take at least the ping time to the server. In v4 in > some situations the client can do the open with no call to the server at > all--by comparison such an open is almost instantaneous. If you're > doing a ton of opens all in a row, that may make a difference.) > In existing v3, you mean even if a file is cached locally by client, in each open, the file attributes need to be read from NFS server everytime? But I just wonder without reading the NFS server, how the consistency was maintained... Thanks.