From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 5/5] virtio-scsi: introduce multiqueue support Date: Tue, 4 Sep 2012 15:48:00 +0300 Message-ID: <20120904124800.GE9805@redhat.com> References: <1346154857-12487-1-git-send-email-pbonzini@redhat.com> <1346154857-12487-6-git-send-email-pbonzini@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1346154857-12487-6-git-send-email-pbonzini@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: Paolo Bonzini 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 On Tue, Aug 28, 2012 at 01:54:17PM +0200, Paolo Bonzini wrote: > This patch adds queue steering to virtio-scsi. When a target is sent > multiple requests, we always drive them to the same queue so that FIFO > processing order is kept. However, if a target was idle, we can choose > a queue arbitrarily. In this case the queue is chosen according to the > current VCPU, so the driver expects the number of request queues to be > equal to the number of VCPUs. This makes it easy and fast to select > the queue, and also lets the driver optimize the IRQ affinity for the > virtqueues (each virtqueue's affinity is set to the CPU that "owns" > the queue). > > Signed-off-by: Paolo Bonzini I guess an alternative is a per-target vq. Is the reason you avoid this that you expect more targets than cpus? If yes this is something you might want to mention in the log.