Return-Path: Received: from aserp1040.oracle.com ([141.146.126.69]:33025 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755217AbcDKUiu convert rfc822-to-8bit (ORCPT ); Mon, 11 Apr 2016 16:38:50 -0400 Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: [PATCH v1 05/18] xprtrdma: Avoid using Write list for small NFS READ requests From: Chuck Lever In-Reply-To: <033901d19431$b3725d20$1a571760$@opengridcomputing.com> Date: Mon, 11 Apr 2016 16:38:44 -0400 Cc: linux-rdma@vger.kernel.org, Linux NFS Mailing List Message-Id: <65CBC59F-3005-44FE-8C70-9DDBC8507C9E@oracle.com> References: <20160411200323.20531.8893.stgit@manet.1015granger.net> <20160411201050.20531.53651.stgit@manet.1015granger.net> <033901d19431$b3725d20$1a571760$@opengridcomputing.com> To: Steve Wise Sender: linux-nfs-owner@vger.kernel.org List-ID: > On Apr 11, 2016, at 4:35 PM, Steve Wise wrote: > >> Avoid the latency and interrupt overhead of registering a Write >> chunk when handling NFS READ requests of a few hundred bytes or >> less. >> >> This change does not interoperate with Linux NFS/RDMA servers >> that do not have commit 9d11b51ce7c1 ('svcrdma: Fix send_reply() >> scatter/gather set-up'). >> >> $ git describe 9d11b51ce7c1 >> v4.2-rc3-10-g9d11b51 >> > > Hey Chuck, > > Is there any way to avoid breaking interoperability with older servers? No, pre-4.2 Linux servers have a bug that can be fixed by applying the above commit, which shouldn't be difficult to backport. Clients have always been allowed to send NFS READ this way. -- Chuck Lever