From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:52589) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hEdb7-0001qM-OK for qemu-devel@nongnu.org; Thu, 11 Apr 2019 13:34:50 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hEdb4-0007Iu-VD for qemu-devel@nongnu.org; Thu, 11 Apr 2019 13:34:49 -0400 Received: from userp2120.oracle.com ([156.151.31.85]:36504) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hEdb4-0007EG-1v for qemu-devel@nongnu.org; Thu, 11 Apr 2019 13:34:46 -0400 Date: Thu, 11 Apr 2019 20:34:20 +0300 From: Yuval Shaia Message-ID: <20190411173419.GB6259@lap1> References: <20190411110157.14252-1-yuval.shaia@oracle.com> <20190411190215.2163572e.cohuck@redhat.com> <20190411172402.GA14509@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190411172402.GA14509@mellanox.com> Subject: Re: [Qemu-devel] [RFC 0/3] VirtIO RDMA List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Jason Gunthorpe Cc: Cornelia Huck , "virtualization@lists.linux-foundation.org" , "qemu-devel@nongnu.org" , "mst@redhat.com" , "marcel.apfelbaum@gmail.com" , "linux-rdma@vger.kernel.org" On Thu, Apr 11, 2019 at 05:24:08PM +0000, Jason Gunthorpe wrote: > On Thu, Apr 11, 2019 at 07:02:15PM +0200, Cornelia Huck wrote: > > On Thu, 11 Apr 2019 14:01:54 +0300 > > Yuval Shaia wrote: > > > > > Data center backends use more and more RDMA or RoCE devices and more and > > > more software runs in virtualized environment. > > > There is a need for a standard to enable RDMA/RoCE on Virtual Machines. > > > > > > Virtio is the optimal solution since is the de-facto para-virtualizaton > > > technology and also because the Virtio specification > > > allows Hardware Vendors to support Virtio protocol natively in order to > > > achieve bare metal performance. > > > > > > This RFC is an effort to addresses challenges in defining the RDMA/RoCE > > > Virtio Specification and a look forward on possible implementation > > > techniques. > > > > > > Open issues/Todo list: > > > List is huge, this is only start point of the project. > > > Anyway, here is one example of item in the list: > > > - Multi VirtQ: Every QP has two rings and every CQ has one. This means that > > > in order to support for example 32K QPs we will need 64K VirtQ. Not sure > > > that this is reasonable so one option is to have one for all and > > > multiplex the traffic on it. This is not good approach as by design it > > > introducing an optional starvation. Another approach would be multi > > > queues and round-robin (for example) between them. > > > > > > Expectations from this posting: > > > In general, any comment is welcome, starting from hey, drop this as it is a > > > very bad idea, to yeah, go ahead, we really want it. > > > Idea here is that since it is not a minor effort i first want to know if > > > there is some sort interest in the community for such device. > > > > My first reaction is: Sounds sensible, but it would be good to have a > > spec for this :) > > I'm unclear why you'd want to have a virtio queue for anything other > that some kind of command channel. > > I'm not sure a QP or CQ benefits from this?? Virtqueue is a standard mechanism to pass data from guest to host. By saying that - it really sounds like QP send and recv rings. So my thought is to use a standard way for rings. As i've learned this is how it is used by other virtio devices ex virtio-net. > > Jason From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.2 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF7ECC10F13 for ; Thu, 11 Apr 2019 17:38:42 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3E6812084D for ; Thu, 11 Apr 2019 17:38:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="PuAXpQ+M" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3E6812084D Authentication-Results: mail.kernel.org; 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Thu, 11 Apr 2019 17:34:33 +0000 Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x3BHYWSu029011; Thu, 11 Apr 2019 17:34:32 GMT Received: from lap1 (/77.138.183.59) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 11 Apr 2019 10:34:31 -0700 Date: Thu, 11 Apr 2019 20:34:20 +0300 From: Yuval Shaia To: Jason Gunthorpe Message-ID: <20190411173419.GB6259@lap1> References: <20190411110157.14252-1-yuval.shaia@oracle.com> <20190411190215.2163572e.cohuck@redhat.com> <20190411172402.GA14509@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline In-Reply-To: <20190411172402.GA14509@mellanox.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9224 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904110117 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9224 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904110117 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] X-Received-From: 156.151.31.85 Subject: Re: [Qemu-devel] [RFC 0/3] VirtIO RDMA X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "mst@redhat.com" , "linux-rdma@vger.kernel.org" , Cornelia Huck , "qemu-devel@nongnu.org" , "virtualization@lists.linux-foundation.org" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Message-ID: <20190411173420.79v-71trxOfmYw-Xqs83ajCrMNmDUbPy_OUbhoSeSc4@z> On Thu, Apr 11, 2019 at 05:24:08PM +0000, Jason Gunthorpe wrote: > On Thu, Apr 11, 2019 at 07:02:15PM +0200, Cornelia Huck wrote: > > On Thu, 11 Apr 2019 14:01:54 +0300 > > Yuval Shaia wrote: > > > > > Data center backends use more and more RDMA or RoCE devices and more and > > > more software runs in virtualized environment. > > > There is a need for a standard to enable RDMA/RoCE on Virtual Machines. > > > > > > Virtio is the optimal solution since is the de-facto para-virtualizaton > > > technology and also because the Virtio specification > > > allows Hardware Vendors to support Virtio protocol natively in order to > > > achieve bare metal performance. > > > > > > This RFC is an effort to addresses challenges in defining the RDMA/RoCE > > > Virtio Specification and a look forward on possible implementation > > > techniques. > > > > > > Open issues/Todo list: > > > List is huge, this is only start point of the project. > > > Anyway, here is one example of item in the list: > > > - Multi VirtQ: Every QP has two rings and every CQ has one. This means that > > > in order to support for example 32K QPs we will need 64K VirtQ. Not sure > > > that this is reasonable so one option is to have one for all and > > > multiplex the traffic on it. This is not good approach as by design it > > > introducing an optional starvation. Another approach would be multi > > > queues and round-robin (for example) between them. > > > > > > Expectations from this posting: > > > In general, any comment is welcome, starting from hey, drop this as it is a > > > very bad idea, to yeah, go ahead, we really want it. > > > Idea here is that since it is not a minor effort i first want to know if > > > there is some sort interest in the community for such device. > > > > My first reaction is: Sounds sensible, but it would be good to have a > > spec for this :) > > I'm unclear why you'd want to have a virtio queue for anything other > that some kind of command channel. > > I'm not sure a QP or CQ benefits from this?? Virtqueue is a standard mechanism to pass data from guest to host. By saying that - it really sounds like QP send and recv rings. So my thought is to use a standard way for rings. As i've learned this is how it is used by other virtio devices ex virtio-net. > > Jason