Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S973364AbdDXQQK (ORCPT ); Mon, 24 Apr 2017 12:16:10 -0400 Received: from ale.deltatee.com ([207.54.116.67]:45006 "EHLO ale.deltatee.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S973309AbdDXQOt (ORCPT ); Mon, 24 Apr 2017 12:14:49 -0400 To: Knut Omang , Benjamin Herrenschmidt , Dan Williams References: <1490911959-5146-1-git-send-email-logang@deltatee.com> <1491974532.7236.43.camel@kernel.crashing.org> <5ac22496-56ec-025d-f153-140001d2a7f9@deltatee.com> <1492034124.7236.77.camel@kernel.crashing.org> <81888a1e-eb0d-cbbc-dc66-0a09c32e4ea2@deltatee.com> <20170413232631.GB24910@bhelgaas-glaptop.roam.corp.google.com> <20170414041656.GA30694@obsidianresearch.com> <1492169849.25766.3.camel@kernel.crashing.org> <630c1c63-ff17-1116-e069-2b8f93e50fa2@deltatee.com> <20170414190452.GA15679@bhelgaas-glaptop.roam.corp.google.com> <1492207643.25766.18.camel@kernel.crashing.org> <1492311719.25766.37.camel@kernel.crashing.org> <5e43818e-8c6b-8be8-23ff-b798633d2a73@deltatee.com> <1492381907.25766.49.camel@kernel.crashing.org> <1493019397.3171.118.camel@oracle.com> Cc: Bjorn Helgaas , Jason Gunthorpe , Christoph Hellwig , Sagi Grimberg , "James E.J. Bottomley" , "Martin K. Petersen" , Jens Axboe , Steve Wise , Stephen Bates , Max Gurtovoy , Keith Busch , linux-pci@vger.kernel.org, linux-scsi , linux-nvme@lists.infradead.org, linux-rdma@vger.kernel.org, linux-nvdimm , "linux-kernel@vger.kernel.org" , Jerome Glisse From: Logan Gunthorpe Message-ID: <9b6c0830-a728-c7ca-e6c6-2135f3f760ed@deltatee.com> Date: Mon, 24 Apr 2017 10:14:35 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <1493019397.3171.118.camel@oracle.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 172.16.1.111 X-SA-Exim-Rcpt-To: jglisse@redhat.com, linux-kernel@vger.kernel.org, linux-nvdimm@ml01.01.org, linux-rdma@vger.kernel.org, linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, linux-pci@vger.kernel.org, keith.busch@intel.com, maxg@mellanox.com, sbates@raithlin.com, swise@opengridcomputing.com, axboe@kernel.dk, martin.petersen@oracle.com, jejb@linux.vnet.ibm.com, sagi@grimberg.me, hch@lst.de, jgunthorpe@obsidianresearch.com, helgaas@kernel.org, dan.j.williams@intel.com, benh@kernel.crashing.org, knut.omang@oracle.com X-SA-Exim-Mail-From: logang@deltatee.com Subject: Re: [RFC 0/8] Copy Offload with Peer-to-Peer PCI Memory X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:24:06 +0000) X-SA-Exim-Scanned: Yes (on ale.deltatee.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 750 Lines: 16 On 24/04/17 01:36 AM, Knut Omang wrote: > My first reflex when reading this thread was to think that this whole domain > lends it self excellently to testing via Qemu. Could it be that doing this in > the opposite direction might be a safer approach in the long run even though > (significant) more work up-front? That's an interesting idea. We did do some very limited testing on qemu with one iteration of our work. However, it's difficult because there is no support for any RDMA devices which are a part of our primary use case. I also imagine it would be quite difficult to develop those models given the array of hardware that needs to be supported and the deep functional knowledge required to figure out appropriate restrictions. Logan