[libvirt] [Question] vhost-user hotplug: multiqueue hotplug seems doesn't pass mq and vectors
Michal Privoznik
mprivozn at redhat.com
Wed Nov 30 08:45:15 UTC 2016
On 30.11.2016 08:41, Gaohaifeng (A) wrote:
> Hi ALL:
> Recently I review the vhost-user hotplug codes, when attach a vhost-user nic with multiqueue, it seems that it doesn't pass mq=on and vectors num to qemu.
> Is there any special consideration or just a small mistake? Parts of codes:
>
> qemuDomainAttachNetDevice(vhostfdSize is 0 when type is vhost-user)
> qemuBuildNicDevStr:
> if (usingVirtio && vhostfdSize > 1) {
> if (net->info.type == VIR_DOMAIN_DEVICE_ADDRESS_TYPE_CCW) {
> /* ccw provides a one to one relation of fds to queues and
> * does not support the vectors option
> */
> virBufferAddLit(&buf, ",mq=on");
> } else {
> /* As advised at http://www.linux-kvm.org/page/Multiqueue
> * we should add vectors=2*N+2 where N is the vhostfdSize
> */
> virBufferAsprintf(&buf, ",mq=on,vectors=%zu", 2 * vhostfdSize + 2);
> }
> }
Ah, probably the latter. Frankly, I don't have idea whether we should
pass vectors= too. Do you?
Michal
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