Messages in this thread | | | Date | Tue, 04 Sep 2012 16:55:56 +0200 | From | Paolo Bonzini <> | Subject | Re: [PATCH 5/5] virtio-scsi: introduce multiqueue support |
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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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