On 11/21/19 12:02 AM, Jason Wang wrote:
> By specifying queues property like:
>
> <devices>
>
> <interface type='network'>
> <source network='default'/>
> <target dev='vnet1'/>
> <model type='virtio'/>
> <driver name='vhost' txmode='iothread' ioeventfd='on'
> event_idx='off' queues='5' rx_queue_size='256' tx_queue_size='256'>
I can not check this because the 3.0 version of libvirt does not support
tx_queue_size. It is multiqueue (queues=5 in the example) setting that
needs to be set to 2*Nvcpus for XDP, correct?
> <host csum='off' gso='off' tso4='off' tso6='off' ecn='off'
> ufo='off' mrg_rxbuf='off'/>
> <guest csum='off' tso4='off' tso6='off' ecn='off' ufo='off'/>
> </driver>
> </interface>
> </devices>
>
>
The virtio_net driver suggests the queues are needed for XDP_TX:
/* XDP requires extra queues for XDP_TX */
if (curr_qp + xdp_qp > vi->max_queue_pairs) {
NL_SET_ERR_MSG_MOD(extack, "Too few free TX rings
available");
netdev_warn(dev, "request %i queues but max is %i\n",
curr_qp + xdp_qp, vi->max_queue_pairs);
return -ENOMEM;
}
Doubling the number of queues for each tap device adds overhead to the
hypervisor if you only want to allow XDP_DROP or XDP_DIRECT. Am I
understanding that correctly?
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