On Tue, Sep 04, 2012 at 04:55:56PM +0200, Paolo Bonzini wrote: > 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.
Well interrupts will go to CPU different from the one that sends commands so ... > > 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 3. use per target queue if less targets than cpus? -- MST -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html