Return-Path: Received: from mail-bn1on0059.outbound.protection.outlook.com ([157.56.110.59]:64512 "EHLO na01-bn1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S964918AbbEFH1w (ORCPT ); Wed, 6 May 2015 03:27:52 -0400 Message-ID: <5549BE30.8020505@sandisk.com> Date: Wed, 6 May 2015 09:09:36 +0200 From: Bart Van Assche MIME-Version: 1.0 To: Christoph Hellwig , Tom Talpey CC: Chuck Lever , Linux NFS Mailing List , Subject: Re: [PATCH v1 00/16] NFS/RDMA patches proposed for 4.1 References: <20150313211124.22471.14517.stgit@manet.1015granger.net> <20150505154411.GA16729@infradead.org> <5E1B32EA-9803-49AA-856D-BF0E1A5DFFF4@oracle.com> <20150505172540.GA19442@infradead.org> <55490886.4070502@talpey.com> <20150505191012.GA21164@infradead.org> <55492ED3.7000507@talpey.com> <20150505210627.GA5941@infradead.org> In-Reply-To: <20150505210627.GA5941@infradead.org> Content-Type: text/plain; charset="windows-1252"; format=flowed Sender: linux-nfs-owner@vger.kernel.org List-ID: On 05/05/15 23:06, Christoph Hellwig wrote: > The contiguous requirements isn't something we can alway guarantee. > While a lot of I/O will have that form the form where there are holes > can happen, although it's not common. Indeed. That is why there is code in the SRP initiator that uses multiple FRWR registrations when a discontiguous SG-list is passed to that driver by the SCSI mid-layer. Some time ago I had posted a test program that makes the SCSI mid-layer submit a discontiguous I/O request to a SCSI LLD (see also https://www.mail-archive.com/linux-rdma@vger.kernel.org/msg21224.html). Bart.