From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 147CA42941; Fri, 14 Apr 2023 14:07:03 +0200 (CEST) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 8439640144; Fri, 14 Apr 2023 14:07:03 +0200 (CEST) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by mails.dpdk.org (Postfix) with ESMTP id 1521E400D5 for ; Fri, 14 Apr 2023 14:07:01 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681474021; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=iLYFhpKNUZfF1PmZnqeYV+Ijhe32mt1NPt8cmZH0ov0=; b=KSM88pj/9ttT0blvDbD+fc5pKeBcNU4GQ8lr5sCZkjYX+5iVyCFwqKsK4q3u5nMxbghODM srE2/fOEOj0dulL/gUdLj61nSZkCyHerHQuDl1eEbaXWy8UoG/zxEolfNUgZNrOunDILBA GcQHiEYYgNkO/b4SSUaGZt3P8me/K0A= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-324-cA9Tfw-bOHWzDONx-QRXMQ-1; Fri, 14 Apr 2023 08:06:58 -0400 X-MC-Unique: cA9Tfw-bOHWzDONx-QRXMQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 090961C087B2; Fri, 14 Apr 2023 12:06:58 +0000 (UTC) Received: from [10.39.208.7] (unknown [10.39.208.7]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 765AD2027045; Fri, 14 Apr 2023 12:06:55 +0000 (UTC) Message-ID: <94efd072-ae82-60ca-a84b-529b69db2810@redhat.com> Date: Fri, 14 Apr 2023 14:06:54 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [RFC 00/27] Add VDUSE support to Vhost library To: Ferruh Yigit , "Xia, Chenbo" , =?UTF-8?Q?Morten_Br=c3=b8rup?= , "dev@dpdk.org" , "david.marchand@redhat.com" , "mkp@redhat.com" , "fbl@redhat.com" , "jasowang@redhat.com" , "Liang, Cunming" , "Xie, Yongji" , "echaudro@redhat.com" , "eperezma@redhat.com" , "amorenoz@redhat.com" References: <20230331154259.1447831-1-maxime.coquelin@redhat.com> <3789c0c7-281b-89c3-45aa-3d985736b04a@amd.com> <107f53d8-c0c3-68a8-1857-4b6ef0165b48@redhat.com> <98CBD80474FA8B44BF855DF32C47DC35D8786B@smartserver.smartshare.dk> <58480498-8037-ec45-548a-8027e185fcaf@redhat.com> From: Maxime Coquelin In-Reply-To: X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On 4/14/23 12:48, Ferruh Yigit wrote: > On 4/13/2023 8:59 AM, Maxime Coquelin wrote: >> Hi, >> >> On 4/13/23 09:08, Xia, Chenbo wrote: >>>> -----Original Message----- >>>> From: Morten Brørup >>>> Sent: Thursday, April 13, 2023 3:41 AM >>>> To: Maxime Coquelin ; Ferruh Yigit >>>> ; dev@dpdk.org; david.marchand@redhat.com; Xia, >>>> Chenbo ; mkp@redhat.com; fbl@redhat.com; >>>> jasowang@redhat.com; Liang, Cunming ; Xie, >>>> Yongji >>>> ; echaudro@redhat.com; eperezma@redhat.com; >>>> amorenoz@redhat.com >>>> Subject: RE: [RFC 00/27] Add VDUSE support to Vhost library >>>> >>>>> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com] >>>>> Sent: Wednesday, 12 April 2023 17.28 >>>>> >>>>> Hi Ferruh, >>>>> >>>>> On 4/12/23 13:33, Ferruh Yigit wrote: >>>>>> On 3/31/2023 4:42 PM, Maxime Coquelin wrote: >>>>>>> This series introduces a new type of backend, VDUSE, >>>>>>> to the Vhost library. >>>>>>> >>>>>>> VDUSE stands for vDPA device in Userspace, it enables >>>>>>> implementing a Virtio device in userspace and have it >>>>>>> attached to the Kernel vDPA bus. >>>>>>> >>>>>>> Once attached to the vDPA bus, it can be used either by >>>>>>> Kernel Virtio drivers, like virtio-net in our case, via >>>>>>> the virtio-vdpa driver. Doing that, the device is visible >>>>>>> to the Kernel networking stack and is exposed to userspace >>>>>>> as a regular netdev. >>>>>>> >>>>>>> It can also be exposed to userspace thanks to the >>>>>>> vhost-vdpa driver, via a vhost-vdpa chardev that can be >>>>>>> passed to QEMU or Virtio-user PMD. >>>>>>> >>>>>>> While VDUSE support is already available in upstream >>>>>>> Kernel, a couple of patches are required to support >>>>>>> network device type: >>>>>>> >>>>>>> https://gitlab.com/mcoquelin/linux/-/tree/vduse_networking_poc >>>>>>> >>>>>>> In order to attach the created VDUSE device to the vDPA >>>>>>> bus, a recent iproute2 version containing the vdpa tool is >>>>>>> required. >>>>>> >>>>>> Hi Maxime, >>>>>> >>>>>> Is this a replacement to the existing DPDK vDPA framework? What is the >>>>>> plan for long term? >>>>>> >>>>> >>>>> No, this is not a replacement for DPDK vDPA framework. >>>>> >>>>> We (Red Hat) don't have plans to support DPDK vDPA framework in our >>>>> products, but there are still contribution to DPDK vDPA by several vDPA >>>>> hardware vendors (Intel, Nvidia, Xilinx), so I don't think it is going >>>>> to be deprecated soon. >>>> >>>> Ferruh's question made me curious... >>>> >>>> I don't know anything about VDUSE or vDPA, and don't use any of it, so >>>> consider me ignorant in this area. >>>> >>>> Is VDUSE an alternative to the existing DPDK vDPA framework? What are >>>> the >>>> differences, e.g. in which cases would an application developer (or >>>> user) >>>> choose one or the other? >>> >>> Maxime should give better explanation.. but let me just explain a bit. >>> >>> Vendors have vDPA HW that support vDPA framework (most likely in their >>> DPU/IPU >>> products). This work is introducing a way to emulate a SW vDPA device in >>> userspace (DPDK), and this SW vDPA device also supports vDPA framework. >>> >>> So it's not an alternative to existing DPDK vDPA framework :) >> >> Correct. >> >> When using DPDK vDPA, the datapath of a Vhost-user port is offloaded to >> a compatible physical NIC (i.e. a NIC that implements Virtio rings >> support), the control path remains the same as a regular Vhost-user >> port, i.e. it provides a Vhost-user unix socket to the application (like >> QEMU or DPDK Virtio-user PMD). >> >> When using Kernel vDPA, the datapath is also offloaded to a vDPA >> compatible device, and the control path is managed by the vDPA bus. >> It can either be consumed by a Kernel Virtio device (here Virtio-net) >> when using Virtio-vDPA. In this case the device is exposed as a regular >> netdev and, in the case of Kubernetes, can be used as primary interfaces >> for the pods. >> Or it can be exposed to user-space via Vhost-vDPA, a chardev that can be >> seen as an alternative to Vhost-user sockets. In this case it can for >> example be used by QEMU or DPDK Virtio-user PMD. In Kubernetes, it can >> be used as a secondary interface. >> >> Now comes VDUSE. VDUSE is a Kernel vDPA device, but instead of being a >> physical device where the Virtio datapath is offloaded, the Virtio >> datapath is offloaded to a user-space application. With this series, a >> DPDK application, like OVS-DPDK for instance, can create VDUSE device >> and expose them either as regular netdev when binding them to Kernel >> Virtio-net driver via Virtio-vDPA, or as Vhost-vDPA interface to be >> consumed by another userspace appliation like QEMU or DPDK application >> using Virtio-user PMD. With this solution, OVS-DPDK could serve both >> primary and secondary interfaces of Kubernetes pods. >> >> I hope it clarifies, I will add these information in the cover-letter >> for next revisions. Let me know if anything is still unclear. >> >> I did a presentation at last DPDK summit [0], maybe the diagrams will >> help to clarify furthermore. >> > > Thanks Chenbo, Maxime for clarification. > > After reading a little more (I think) I got it better, slides [0] were > useful. > > So this is more like a backend/handler, similar to vhost-user, although > it is vDPA device emulation. > Can you please describe more the benefit of vduse comparing to vhost-user? The main benefit is that VDUSE device can be exposed as a regular netdev, while this is not possible with Vhost-user. > Also what is "VDUSE daemon", which is referred a few times in > documentation, is it another userspace implementation of the vduse? VDUSE daemon is the application that implements the VDUSE device, e.g. OVS-DPDK with DPDK Vhost library using this series in our case. Maxime > >>>> >>>> And if it is a better alternative, perhaps the documentation should >>>> mention that it is recommended over DPDK vDPA. Just like we started >>>> recommending alternatives to the KNI driver, so we could phase it out >>>> and >>>> eventually get rid of it. >>>> >>>>> >>>>> Regards, >>>>> Maxime >>> >> >> [0]: >> https://static.sched.com/hosted_files/dpdkuserspace22/9f/Open%20DPDK%20to%20containers%20networking%20with%20VDUSE.pdf >> >