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[79.178.2.19]) by smtp.gmail.com with ESMTPSA id 11sm21228306qkr.101.2020.03.08.05.17.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 08 Mar 2020 05:17:53 -0700 (PDT) Date: Sun, 8 Mar 2020 08:17:48 -0400 From: "Michael S. Tsirkin" To: Yuri Benditovich Subject: Re: [PATCH 0/3] reference implementation of RSS Message-ID: <20200308081509-mutt-send-email-mst@kernel.org> References: <20200226174809.9675-1-yuri.benditovich@daynix.com> <87242152-5823-59a0-b0ce-2aa555559391@redhat.com> <20200308040540-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Disposition: inline X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 205.139.110.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Yan Vugenfirer , Jason Wang , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Sun, Mar 08, 2020 at 11:56:38AM +0200, Yuri Benditovich wrote: > On Sun, Mar 8, 2020 at 10:06 AM Michael S. Tsirkin wrote= : > > > > On Fri, Mar 06, 2020 at 11:50:30AM +0200, Yuri Benditovich wrote: > > > > > > > > > On Fri, Mar 6, 2020 at 11:27 AM Jason Wang wrot= e: > > > > > > > > > On 2020/2/27 =E4=B8=8A=E5=8D=881:48, Yuri Benditovich wrote: > > > > Support for VIRTIO_NET_F_RSS feature in QEMU for reference > > > > purpose. Implements Toeplitz hash calculation for incoming > > > > packets according to configuration provided by driver. > > > > > > > > This series requires previously submitted and accepted > > > > patch to be applied: > > > > https://lists.gnu.org/archive/html/qemu-devel/2020-01/msg06448.= html > > > > > > > > Yuri Benditovich (3): > > > > virtio-net: introduce RSS RX steering feature > > > > virtio-net: implement RSS configuration command > > > > virtio-net: implement RX RSS processing > > > > > > > > hw/net/trace-events | 3 + > > > > hw/net/virtio-net.c | 234 > > > +++++++++++++++++++-VIRTIO_NET_F_RSS > > > > include/hw/virtio/virtio-net.h | 12 + > > > > include/standard-headers/linux/virtio_net.h | 37 +++- > > > > 4 files changed, 273 insertions(+), 13 deletions(-) > > > > > > > > > > One question before the reviewing. > > > > > > Do we need to deal with migration (which I think yes)? > > > > > > > > > I think we don't (yet) as this is a reference implementation and the = main goal > > > is to provide the functional reference for hardware solution. > > > > > > That's fine, but then we must block migration, and add appropriate code > > comments. Just silently losing data isn't a good idea. >=20 > Note that there is no data lost, just the configuration of RSS is not mig= rating. > So, qemu just will not redirect the data to different queues after migrat= ion. Right. Unlike auto-mq, the spec doesn't say the direction is best effort th= ough, so that would be a spec violation. > I would add the migration prevention in the next series with > implementation of hash delivery to prevent different packet sizes in > driver and qemu. And hopefully full migration support will follow. One other thing to check is vhost - I didn't check what happens with this patchset but I think at a minimum we need to fail vhost init, until the backend implements the feature biit. > > > > > I agree with the general direction that for complete support of RSS a= nd hash > > > delivery the best way is to do that in kernel using bpf. > > > For that, IMO, the bpf should be a part of the kernel (it uses skb fi= elds) and > > > the tap should receive just RSS parameters for it. > > > At this stage we definitely will need to add migration support and pr= opagation > > > of RSS parameters. > > > > > > > > > > > > Thanks > > > > > > > >