Return-Path: Received: from mail-gx0-f174.google.com ([209.85.161.174]:43391 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758319Ab0HDVMS convert rfc822-to-8bit (ORCPT ); Wed, 4 Aug 2010 17:12:18 -0400 Received: by gxk23 with SMTP id 23so2174282gxk.19 for ; Wed, 04 Aug 2010 14:12:17 -0700 (PDT) In-Reply-To: <97A00951-577C-4365-AA38-3C6E2D03B372@netapp.com> References: <97A00951-577C-4365-AA38-3C6E2D03B372@netapp.com> From: Yudong Gao Date: Wed, 4 Aug 2010 14:11:57 -0700 Message-ID: Subject: Re: Write delegation To: Andy Adamson Cc: linux-nfs@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: MIME-Version: 1.0 Thanks for the reply, Andy! So the write delegation can only reduce the unnecessary open/close and lock/locku. But if a client modify the same page for multiple times, e.g. editing the file in a editor, is there any optimization to prevent the client from sending the half-updated pages? Ideally only the final update need to be put on the wire. Thanks! best, Yudong On Wed, Aug 4, 2010 at 1:59 PM, Andy Adamson wrote: > > On Aug 4, 2010, at 3:21 PM, Yudong Gao wrote: > >> Hi, >> >> I am not able to find the implementation of directory delegation, >> either. Similarly, the callback functions CB_NOTIFY is not >> implemented, either. I find that in preprocss_nfs41_op() in >> callback_xdr.c, whenever a CB_NOTIFY is encountered, an >> NFS4ERR_NOTSUPP is returned directly. > > CB_NOTIFY is not currently supported on the Linux NFS client. > >> >> Am I missing something? Or they are just not supported in the current version? >> >> Thanks a lot! >> >> best, >> >> Yudong >> >> On Mon, Aug 2, 2010 at 5:17 PM, Yudong Gao wrote: >>> Hi, >>> >>> I am looking at the delegation implementation in the source code of >>> NFS 4.1 in kernel 2.6.32.15. I can find the code for read delegation, >>> which is working and can serve the read requests locally. But I can >>> never find the code about write delegation, which is supposed to cache >>> the write update locally. I try to look at the functions including >>> nfs_writepage(s), nfs_file_flush() but none of them checks or uses the >>> write delegation. >>> >>> Is write delegation currently implemented in NFS 4.1? > > Write delegation is supported but I don't think write behavior changes - writes are still cached and flushed as without a write delegation. The write delegation does prevent open/close and lock/locku from being put on the wire. > > -->Andy > >>> >>> Thanks! >>> >>> best, >>> >>> Yudong >>> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at ?http://vger.kernel.org/majordomo-info.html > >