From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47927) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dDngu-0007wk-Kb for qemu-devel@nongnu.org; Thu, 25 May 2017 04:00:19 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dDngo-000168-2E for qemu-devel@nongnu.org; Thu, 25 May 2017 04:00:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54858) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dDngn-000153-Os for qemu-devel@nongnu.org; Thu, 25 May 2017 04:00:09 -0400 References: <1494578148-102868-1-git-send-email-wei.w.wang@intel.com> <591AA65F.8080608@intel.com> <7e1b48d5-83e6-a0ae-5d91-696d8db09d7c@redhat.com> <591D0EF5.9000807@intel.com> <20170519153329.GA30573@stefanha-x1.localdomain> <286AC319A985734F985F78AFA26841F7392351DD@shsmsx102.ccr.corp.intel.com> <7ff05785-6bca-a886-0eb0-aeeb0f8d8e1a@redhat.com> <5923CCF2.2000001@intel.com> <3d9e8375-fbaa-c011-8242-b37cd971069b@redhat.com> <5924136A.4090004@intel.com> <7636d3d0-a0de-f9a6-47f8-2d09a448b978@redhat.com> <592544D9.5010100@intel.com> From: Jason Wang Message-ID: <23dac05e-ba3d-df6d-4831-feab9be1c6d2@redhat.com> Date: Thu, 25 May 2017 15:59:58 +0800 MIME-Version: 1.0 In-Reply-To: <592544D9.5010100@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [virtio-dev] Re: [virtio-dev] Re: [PATCH v2 00/16] Vhost-pci for inter-VM communication List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wei Wang , Stefan Hajnoczi Cc: "virtio-dev@lists.oasis-open.org" , "pbonzini@redhat.com" , "marcandre.lureau@gmail.com" , "qemu-devel@nongnu.org" , "mst@redhat.com" On 2017=E5=B9=B405=E6=9C=8824=E6=97=A5 16:31, Wei Wang wrote: > On 05/24/2017 11:24 AM, Jason Wang wrote: >> >> >> On 2017=E5=B9=B405=E6=9C=8823=E6=97=A5 18:48, Wei Wang wrote: >>> On 05/23/2017 02:32 PM, Jason Wang wrote: >>>> >>>> >>>> On 2017=E5=B9=B405=E6=9C=8823=E6=97=A5 13:47, Wei Wang wrote: >>>>> On 05/23/2017 10:08 AM, Jason Wang wrote: >>>>>> >>>>>> >>>>>> On 2017=E5=B9=B405=E6=9C=8822=E6=97=A5 19:46, Wang, Wei W wrote: >>>>>>> On Monday, May 22, 2017 10:28 AM, Jason Wang wrote: >>>>>>>> On 2017=E5=B9=B405=E6=9C=8819=E6=97=A5 23:33, Stefan Hajnoczi wr= ote: >>>>>>>>> On Fri, May 19, 2017 at 11:10:33AM +0800, Jason Wang wrote: >>>>>>>>>> On 2017=E5=B9=B405=E6=9C=8818=E6=97=A5 11:03, Wei Wang wrote: >>>>>>>>>>> On 05/17/2017 02:22 PM, Jason Wang wrote: >>>>>>>>>>>> On 2017=E5=B9=B405=E6=9C=8817=E6=97=A5 14:16, Jason Wang wro= te: >>>>>>>>>>>>> On 2017=E5=B9=B405=E6=9C=8816=E6=97=A5 15:12, Wei Wang wrot= e: >>>>>>>>>>>>>>> Hi: >>>>>>>>>>>>>>> >>>>>>>>>>>>>>> Care to post the driver codes too? >>>>>>>>>>>>>>> >>>>>>>>>>>>>> OK. It may take some time to clean up the driver code=20 >>>>>>>>>>>>>> before post >>>>>>>>>>>>>> it out. You can first have a check of the draft at the=20 >>>>>>>>>>>>>> repo here: >>>>>>>>>>>>>> https://github.com/wei-w-wang/vhost-pci-driver >>>>>>>>>>>>>> >>>>>>>>>>>>>> Best, >>>>>>>>>>>>>> Wei >>>>>>>>>>>>> Interesting, looks like there's one copy on tx side. We=20 >>>>>>>>>>>>> used to >>>>>>>>>>>>> have zerocopy support for tun for VM2VM traffic. Could you=20 >>>>>>>>>>>>> please >>>>>>>>>>>>> try to compare it with your vhost-pci-net by: >>>>>>>>>>>>> >>>>>>>>>>> We can analyze from the whole data path - from VM1's network=20 >>>>>>>>>>> stack >>>>>>>>>>> to send packets -> VM2's network stack to receive packets. Th= e >>>>>>>>>>> number of copies are actually the same for both. >>>>>>>>>> That's why I'm asking you to compare the performance. The=20 >>>>>>>>>> only reason >>>>>>>>>> for vhost-pci is performance. You should prove it. >>>>>>>>> There is another reason for vhost-pci besides maximum=20 >>>>>>>>> performance: >>>>>>>>> >>>>>>>>> vhost-pci makes it possible for end-users to run networking or=20 >>>>>>>>> storage >>>>>>>>> appliances in compute clouds. Cloud providers do not allow=20 >>>>>>>>> end-users >>>>>>>>> to run custom vhost-user processes on the host so you need=20 >>>>>>>>> vhost-pci. >>>>>>>>> >>>>>>>>> Stefan >>>>>>>> Then it has non NFV use cases and the question goes back to the=20 >>>>>>>> performance >>>>>>>> comparing between vhost-pci and zerocopy vhost_net. If it does=20 >>>>>>>> not perform >>>>>>>> better, it was less interesting at least in this case. >>>>>>>> >>>>>>> Probably I can share what we got about vhost-pci and vhost-user: >>>>>>> https://github.com/wei-w-wang/vhost-pci-discussion/blob/master/vh= ost_pci_vs_vhost_user.pdf=20 >>>>>>> >>>>>>> Right now, I don=E2=80=99t have the environment to add the vhost_= net test. >>>>>> >>>>>> Thanks, the number looks good. But I have some questions: >>>>>> >>>>>> - Is the number measured through your vhost-pci kernel driver code= ? >>>>> >>>>> Yes, the kernel driver code. >>>> >>>> Interesting, in the above link, "l2fwd" was used in vhost-pci=20 >>>> testing. I want to know more about the test configuration: If l2fwd=20 >>>> is the one that dpdk had, want to know how can you make it work for=20 >>>> kernel driver. (Maybe packet socket I think?) If not, want to know=20 >>>> how do you configure it (e.g through bridge or act_mirred or=20 >>>> others). And in OVS dpdk, is dpdk l2fwd + pmd used in the testing? >>>> >>> >>> Oh, that l2fwd is a kernel module from OPNFV vsperf >>> (http://artifacts.opnfv.org/vswitchperf/docs/userguide/quickstart.htm= l) >>> For both legacy and vhost-pci cases, they use the same l2fwd module. >>> No bridge is used, the module already works at L2 to forward packets >>> between two net devices. >> >> Thanks for the pointer. Just to confirm, I think virtio-net kernel=20 >> driver is used in OVS-dpdk test? > > Yes. In both cases, the guests are using kernel drivers. > >> >> Another question is, can we manage to remove the copy in tx? If not,=20 >> is it a limitation of virtio protocol? >> > > No, we can't. Use this example, VM1's Vhost-pci<->virtio-net of VM2,=20 > VM1 sees VM2's memory, but > VM2 only sees its own memory. > What this copy achieves is to get data from VM1's memory to VM2's=20 > memory, so that VM2 can deliver it's > own memory to its network stack. Then, as has been pointed out. Should we consider a vhost-pci to=20 vhost-pci peer? Even with vhost-pci to virito-net configuration, I think rx zerocopy=20 could be achieved but not implemented in your driver (probably more=20 easier in pmd). Thanks > > Best, > Wei > > > >