Return-Path: Received: from quartz.orcorp.ca ([184.70.90.242]:44610 "EHLO quartz.orcorp.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751457AbdIFTjw (ORCPT ); Wed, 6 Sep 2017 15:39:52 -0400 Date: Wed, 6 Sep 2017 13:39:46 -0600 From: Jason Gunthorpe To: Chuck Lever Cc: Sagi Grimberg , linux-rdma , Linux NFS Mailing List Subject: Re: [PATCH RFC 0/5] xprtrdma Send completion batching Message-ID: <20170906193946.GC18461@obsidianresearch.com> References: <20170905164347.11106.27140.stgit@manet.1015granger.net> <1230f9d9-07c1-6d00-b197-f408712fb5c1@grimberg.me> <890CC58C-7F8F-4B7E-8620-21F07007D3AA@oracle.com> <6dcdcc25-2613-cdb5-1db2-6c944f05242b@grimberg.me> <4E2E5580-69A5-4C3B-9FCA-E61AE2042E6B@oracle.com> <9059315f-1985-042e-a59f-26a66fbece3e@grimberg.me> <5B2F42B8-2CBD-43F4-BBAD-71EDD4F871FB@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <5B2F42B8-2CBD-43F4-BBAD-71EDD4F871FB@oracle.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: On Wed, Sep 06, 2017 at 02:33:50PM -0400, Chuck Lever wrote: > B. Force RPC completion to wait for Send completion, which > would allow the post-v4.6 scatter-gather code to work > safely. This would need some guarantee that Sends will > always complete in a short period. Why is waiting for the send completion so fundamentally different from waiting for the remote RPC reply? I would say that 99% of time the send completion and RPC reply completion will occure approximately concurrently. eg It is quite likely the RPC reply SEND carries an embeded ack for the requesting SEND.. Jason