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
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