From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 5/5] virtio-scsi: introduce multiqueue support Date: Tue, 04 Sep 2012 16:55:56 +0200 Message-ID: <5046167C.3070109@redhat.com> References: <1346154857-12487-1-git-send-email-pbonzini@redhat.com> <1346154857-12487-6-git-send-email-pbonzini@redhat.com> <20120904144754.GO9805@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20120904144754.GO9805@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 To: "Michael S. Tsirkin" Cc: kvm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org List-Id: linux-scsi@vger.kernel.org Il 04/09/2012 16:47, Michael S. Tsirkin ha scritto: >> > static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq, >> > - struct virtqueue *vq) >> > + struct virtqueue *vq, bool affinity) >> > { >> > spin_lock_init(&virtscsi_vq->vq_lock); >> > virtscsi_vq->vq = vq; >> > + if (affinity) >> > + virtqueue_set_affinity(vq, virtqueue_get_queue_index(vq) - >> > + VIRTIO_SCSI_VQ_BASE); >> > } >> > > This means in practice if you have less virtqueues than CPUs, > things are not going to work well, will they? Not particularly. It could be better or worse than single queue depending on the workload. > Any idea what to do? Two possibilities: 1) Add a stride argument to virtqueue_set_affinity, and make it equal to the number of queues. 2) Make multiqueue the default in QEMU, and make the default number of queues equal to the number of VCPUs. I was going for (2). Paolo