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Tsirkin" To: Willem de Bruijn Subject: Re: [PATCH v3 2/4] drivers/net/virtio_net: Added basic RSS support. Message-ID: <20220220081148-mutt-send-email-mst@kernel.org> References: <20220208181510.787069-1-andrew@daynix.com> <20220208181510.787069-3-andrew@daynix.com> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=mst@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Cc: Andrew Melnichenko , Network Development , LKML , virtualization , Yuri Benditovich , Yan Vugenfirer , Jakub Kicinski , "David S. Miller" X-BeenThere: virtualization@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Linux virtualization List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: virtualization-bounces@lists.linux-foundation.org Sender: "Virtualization" On Fri, Feb 18, 2022 at 08:43:20AM -0700, Willem de Bruijn wrote: > On Thu, Feb 17, 2022 at 12:05 PM Andrew Melnichenko wrote: > > > > Hi all, > > > > On Mon, Feb 14, 2022 at 12:09 AM Willem de Bruijn > > wrote: > > > > > > > > > @@ -3113,13 +3270,14 @@ static int virtnet_probe(struct virtio_device *vdev) > > > > > > u16 max_queue_pairs; > > > > > > int mtu; > > > > > > > > > > > > - /* Find if host supports multiqueue virtio_net device */ > > > > > > - err = virtio_cread_feature(vdev, VIRTIO_NET_F_MQ, > > > > > > - struct virtio_net_config, > > > > > > - max_virtqueue_pairs, &max_queue_pairs); > > > > > > + /* Find if host supports multiqueue/rss virtio_net device */ > > > > > > + max_queue_pairs = 1; > > > > > > + if (virtio_has_feature(vdev, VIRTIO_NET_F_MQ) || virtio_has_feature(vdev, VIRTIO_NET_F_RSS)) > > > > > > + max_queue_pairs = > > > > > > + virtio_cread16(vdev, offsetof(struct virtio_net_config, max_virtqueue_pairs)); > > > > > > > > > > Instead of testing either feature and treating them as somewhat equal, > > > > > shouldn't RSS be dependent on MQ? > > > > > > > > No, RSS is dependent on CTRL_VQ. Technically RSS and MQ are similar features. > > > > > > RSS depends on having multiple queues. > > > > > > What would enabling VIRTIO_NET_F_RSS without VIRTIO_NET_F_MQ do? > > > > RSS would work. > > What does that mean, exactly? RSS is load balancing, does that not > require multi-queue? It does, but VIRTIO_NET_F_MQ is a misnomer. \item[VIRTIO_NET_F_MQ(22)] Device supports multiqueue with automatic receive steering. VIRTIO_NET_F_RSS implies multi queue and does not depend on VIRTIO_NET_F_MQ. -- MST _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization