From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [net-next RFC V5 4/5] virtio_net: multiqueue support Date: Fri, 06 Jul 2012 15:45:38 +0800 Message-ID: <4FF697A2.2000502@redhat.com> References: <1341484194-8108-1-git-send-email-jasowang@redhat.com> <1341484194-8108-5-git-send-email-jasowang@redhat.com> <4FF5F2F2.9050307@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Cc: krkumar2@in.ibm.com, habanero@linux.vnet.ibm.com, mashirle@us.ibm.com, kvm@vger.kernel.org, mst@redhat.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, edumazet@google.com, tahm@linux.vnet.ibm.com, jwhan@filewood.snu.ac.kr, davem@davemloft.net, sri@us.ibm.com To: Amos Kong Return-path: In-Reply-To: <4FF5F2F2.9050307@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org List-Id: netdev.vger.kernel.org On 07/06/2012 04:02 AM, Amos Kong wrote: > On 07/05/2012 06:29 PM, Jason Wang wrote: >> This patch converts virtio_net to a multi queue device. After negotiated >> VIRTIO_NET_F_MULTIQUEUE feature, the virtio device has many tx/rx queue pairs, >> and driver could read the number from config space. >> >> The driver expects the number of rx/tx queue paris is equal to the number of >> vcpus. To maximize the performance under this per-cpu rx/tx queue pairs, some >> optimization were introduced: >> >> - Txq selection is based on the processor id in order to avoid contending a lock >> whose owner may exits to host. >> - Since the txq/txq were per-cpu, affinity hint were set to the cpu that owns >> the queue pairs. >> >> Signed-off-by: Krishna Kumar >> Signed-off-by: Jason Wang >> --- > ... > >> >> static int virtnet_probe(struct virtio_device *vdev) >> { >> - int err; >> + int i, err; >> struct net_device *dev; >> struct virtnet_info *vi; >> + u16 num_queues, num_queue_pairs; >> + >> + /* Find if host supports multiqueue virtio_net device */ >> + err = virtio_config_val(vdev, VIRTIO_NET_F_MULTIQUEUE, >> + offsetof(struct virtio_net_config, >> + num_queues),&num_queues); >> + >> + /* We need atleast 2 queue's */ > > s/atleast/at least/ > > >> + if (err || num_queues< 2) >> + num_queues = 2; >> + if (num_queues> MAX_QUEUES * 2) >> + num_queues = MAX_QUEUES; > num_queues = MAX_QUEUES * 2; > > MAX_QUEUES is the limitation of RX or TX. Right, it's a typo, thanks. >> + >> + num_queue_pairs = num_queues / 2; > ... >