Re: [PATCH net-next RFC 4/4] virtio-net: clean tx descriptors from rx napi

On Mon, Mar 6, 2017 at 12:43 PM, Willem de Bruijn
[off-list ref] wrote:

quoted

quoted

+static void virtnet_poll_cleantx(struct receive_queue *rq)
+{
+       struct virtnet_info *vi = rq->vq->vdev->priv;
+       unsigned int index = vq2rxq(rq->vq);
+       struct send_queue *sq = &vi->sq[index];
+       struct netdev_queue *txq = netdev_get_tx_queue(vi->dev, index);
+
+       __netif_tx_lock(txq, smp_processor_id());
+       free_old_xmit_skbs(sq, sq->napi.weight);
+       __netif_tx_unlock(txq);

Should we check tx napi weight here? Or this was treated as an independent
optimization?

Good point. This was not intended to run in no-napi mode as is.
With interrupts disabled most of the time in that mode, I don't
expect it to be worthwhile using in that case. I'll add the check
for sq->napi.weight != 0.

I'm wrong here. Rx interrupts are not disabled, of course. It is
probably worth benchmarking, then.