Return-Path: Received: from mail-oi0-f54.google.com ([209.85.218.54]:33328 "EHLO mail-oi0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753445AbbC0Rf3 (ORCPT ); Fri, 27 Mar 2015 13:35:29 -0400 Received: by oifl3 with SMTP id l3so82057588oif.0 for ; Fri, 27 Mar 2015 10:35:28 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20150327171631.GC27862@phlsvsds.ph.intel.com> References: <551579CA.4030901@profitbricks.com> <55157B98.1060103@profitbricks.com> <20150327161319.GB28412@obsidianresearch.com> <20150327171631.GC27862@phlsvsds.ph.intel.com> Date: Fri, 27 Mar 2015 18:35:28 +0100 Message-ID: Subject: Re: [RFC PATCH 08/11] IB/Verbs: Use management helper has_iwarp() for, iwarp-check From: Yun Wang To: "ira.weiny" Cc: Jason Gunthorpe , Roland Dreier , Sean Hefty , Hal Rosenstock , "linux-rdma@vger.kernel.org" , linux-kernel , linux-nfs@vger.kernel.org, netdev@vger.kernel.org, "J. Bruce Fields" , Trond Myklebust , "David S. Miller" , Or Gerlitz , Moni Shoua , PJ Waskiewicz , Tatyana Nikolova , Yan Burman , Jack Morgenstein , Bart Van Assche , Yann Droneaud , Colin Ian King , Majd Dibbiny , Jiri Kosina , Matan Barak , Alex Estrin , Doug Ledford , Eric Dumazet , Erez Shitrit , Sagi Grimberg , Haggai Eran , Shachar Raindel , Mike Marciniszyn , Steve Wise , Tom Tucker , Chuck Lever Content-Type: text/plain; charset=UTF-8 Sender: linux-nfs-owner@vger.kernel.org List-ID: On Fri, Mar 27, 2015 at 6:16 PM, ira.weiny wrote: > On Fri, Mar 27, 2015 at 10:13:19AM -0600, Jason Gunthorpe wrote: >> On Fri, Mar 27, 2015 at 04:47:36PM +0100, Michael Wang wrote: >> > >> > Introduce helper has_iwarp() to help us check if an IB device >> > support IWARP protocol. >> >> Should probably be !has_rdma_read_sges() >> >> True if the device can handle more than one SGE entry on a RDMA READ >> work request. > > Isn't this value already provided by the query_device verb? > > The verbs spec states the Query HCA contains the: > > "Maximum number of scatter/gather entries per Work Request supported by the > HCA." I'm not sure but may be query_device() is just too expensive for this path? I need some investigation here too. Regards, Michael Wang > > -- Ira > >> >> Jason