Return-Path: Received: from userp1050.oracle.com ([156.151.31.82]:41782 "EHLO userp1050.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754584AbcHSBKc (ORCPT ); Thu, 18 Aug 2016 21:10:32 -0400 Received: from userp1040.oracle.com (userp1040.oracle.com [156.151.31.81]) by userp1050.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id u7IFR3W7023395 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK) for ; Thu, 18 Aug 2016 15:27:04 GMT Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) Subject: Re: Is NFSv4.2 now compatible & stable with rdma? From: Chuck Lever In-Reply-To: Date: Thu, 18 Aug 2016 11:26:38 -0400 Cc: Linux NFS Mailing List Message-Id: <173CD366-84D2-42B5-8903-3B5E5131095B@oracle.com> References: To: james harvey Sender: linux-nfs-owner@vger.kernel.org List-ID: Hi James- > On Aug 18, 2016, at 12:09 AM, james harvey wrote: > > A year ago, on 7/30/2015, Chuck Lever said NFS/RDMA wasn't yet working > with NFSv4.1 and NFSv4.2, as a known issue. > > I was able to use "vers=4.0" to get around the issue. > > I see v4.2 seems to mount properly, but before switching over to it, I > wanted to see if it's considered stable, or still to be avoided. Can you tell why you'd like to use it? Which NFSv4.2 feature is interesting to you? I don't test it regularly, simply because - The complete tests on each version take a long time to run - NFSv4.2 features are all optional, and the Linux NFSv4.2 implementation adds only a couple that probably won't be affected by RDMA. READ_PLUS will need some attention at some point, but I think Anna is still polishing the upper layer implementation. - I don't have any specific tests for security labels, which add to the size of the NFSv4 GETATTR receive buffer whether labels are actually retrieved or not. So there is a little NFSv4.2 testing we get for free just by using NFSv4.0. - There's yet a lot of non-version-specific work to do on RPC-over-RDMA. The main blocker before was support for bi-directional RPC, which all minorversions of NFSv4 use after mv 1, and that should be working as well as it does for NFSv4.1. NFSv4.2 itself should work, but I might choose to stay with NFSv4.1 for now if it were up to me, unless you have need of one of the new features. For example, there is no standard specification describing how READ_PLUS is supposed to work on RPC-over-RDMA (that's in the works). -- Chuck Lever