On Mon, 9 Nov 2020 17:06:16 +0100
Cornelia Huck <cohuck@redhat.com> wrote:
@@ -20,6 +21,11 @@ static void virtio_ccw_blk_realize(VirtioCcwDevice *ccw_dev,
Error **errp)
{
VirtIOBlkCcw *dev = VIRTIO_BLK_CCW(ccw_dev);
DeviceState *vdev = DEVICE(&dev->vdev);
+ VirtIOBlkConf *conf = &dev->vdev.conf;
+
+ if (conf->num_queues == VIRTIO_BLK_AUTO_NUM_QUEUES) {
+ conf->num_queues = MIN(4, current_machine->smp.cpus);
+ }
I would like to have a comment explaining the numbers here, however.
virtio-pci has a pretty good explanation (use 1:1 for vqs:vcpus if
possible, apply some other capping). 4 seems to be a bit arbitrary
without explanation, although I'm sure you did some measurements :)
Frankly, I don't have any measurements yet. For the secure case,
I think Mimu has assessed the impact of multiqueue, hence adding Mimu to
the cc list. @Mimu can you help us out.
Regarding the normal non-protected VMs I'm in a middle of producing some
measurement data. This was admittedly a bit rushed because of where we
are in the cycle. Sorry to disappoint you.