Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932394AbWHKApF (ORCPT ); Thu, 10 Aug 2006 20:45:05 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932389AbWHKApF (ORCPT ); Thu, 10 Aug 2006 20:45:05 -0400 Received: from pat.uio.no ([129.240.10.4]:47255 "EHLO pat.uio.no") by vger.kernel.org with ESMTP id S932385AbWHKApD (ORCPT ); Thu, 10 Aug 2006 20:45:03 -0400 Subject: Re: Urgent help needed on an NFS question, please help!!! From: Trond Myklebust To: Xin Zhao Cc: Matthew Wilcox , Neil Brown , linux-kernel , linux-fsdevel@vger.kernel.org In-Reply-To: <4ae3c140608101525u7b6eeaebjca351ba850173544@mail.gmail.com> References: <4ae3c140608092204n1c07152k52010a10e209bb77@mail.gmail.com> <17626.49136.384370.284757@cse.unsw.edu.au> <4ae3c140608092254k62dce9at2e8cdcc9ae7a6d9f@mail.gmail.com> <17626.52269.828274.831029@cse.unsw.edu.au> <4ae3c140608100815p57c0378kfd316a482738ee83@mail.gmail.com> <20060810161107.GC4379@parisc-linux.org> <4ae3c140608100923j1ffb5bb5qa776bff79365874c@mail.gmail.com> <1155230922.10547.61.camel@localhost> <4ae3c140608101102j3ec28dccob94d407b9879aa86@mail.gmail.com> <1155239982.5826.24.camel@localhost> <4ae3c140608101525u7b6eeaebjca351ba850173544@mail.gmail.com> Content-Type: text/plain Date: Thu, 10 Aug 2006 20:44:54 -0400 Message-Id: <1155257094.5826.101.camel@localhost> Mime-Version: 1.0 X-Mailer: Evolution 2.6.1 Content-Transfer-Encoding: 7bit X-UiO-Spam-info: not spam, SpamAssassin (score=-0.978, required 12, autolearn=disabled, AWL -0.69, NIGERIAN_SUBJECT2 1.76, PLING_PLING 0.43, RCVD_IN_XBL 2.51, UIO_MAIL_IS_INTERNAL -5.00) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1327 Lines: 27 On Thu, 2006-08-10 at 18:25 -0400, Xin Zhao wrote: > The inter-VM inode helps reduce communication cost used to retrieve > file attributes in a VM environment. In a network environment, it is > possible for a client to direct see the inode caches of the server. > But in the virtual server environment, where both client and server > running on the same physical host, this would be possible. > > If clients have read-only access to server's inode cache, they can > directly retrieve file attributes without incurring expensive > getattr() rpc call. Of couse the delegation is able to allow a client > to trust local cached file attributes without worry about server > change. But this only works when file is not shared by multiple > clients. Right? Does NFS4 has some other mechanisms that can further > improve performance on metadata access? Not metadata access, no. That would require some seriously messy locking rules. It improves performance by allowing a client to access the block device directly for data reads and writes if it has the capability of doing so. Trond - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/