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vhost_net: tx batching
This patch tries to utilize tuntap rx batching by peeking the tx virtqueue during transmission, if there's more available buffers in the virtqueue, set MSG_MORE flag for a hint for backend (e.g tuntap) to batch the packets. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Jason Wang <jasowang@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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275bf960ac
commit
0ed005ce02
1 changed files with 20 additions and 3 deletions
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@ -351,6 +351,15 @@ static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
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return r;
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}
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static bool vhost_exceeds_maxpend(struct vhost_net *net)
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{
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struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
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struct vhost_virtqueue *vq = &nvq->vq;
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return (nvq->upend_idx + vq->num - VHOST_MAX_PEND) % UIO_MAXIOV
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== nvq->done_idx;
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}
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/* Expects to be always run from workqueue - which acts as
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* read-size critical section for our kind of RCU. */
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static void handle_tx(struct vhost_net *net)
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@ -394,8 +403,7 @@ static void handle_tx(struct vhost_net *net)
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/* If more outstanding DMAs, queue the work.
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* Handle upend_idx wrap around
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*/
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if (unlikely((nvq->upend_idx + vq->num - VHOST_MAX_PEND)
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% UIO_MAXIOV == nvq->done_idx))
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if (unlikely(vhost_exceeds_maxpend(net)))
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break;
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head = vhost_net_tx_get_vq_desc(net, vq, vq->iov,
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@ -454,6 +462,16 @@ static void handle_tx(struct vhost_net *net)
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msg.msg_control = NULL;
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ubufs = NULL;
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}
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total_len += len;
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if (total_len < VHOST_NET_WEIGHT &&
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!vhost_vq_avail_empty(&net->dev, vq) &&
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likely(!vhost_exceeds_maxpend(net))) {
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msg.msg_flags |= MSG_MORE;
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} else {
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msg.msg_flags &= ~MSG_MORE;
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}
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/* TODO: Check specific error and bomb out unless ENOBUFS? */
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err = sock->ops->sendmsg(sock, &msg, len);
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if (unlikely(err < 0)) {
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@ -472,7 +490,6 @@ static void handle_tx(struct vhost_net *net)
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vhost_add_used_and_signal(&net->dev, vq, head, 0);
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else
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vhost_zerocopy_signal_used(net, vq);
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total_len += len;
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vhost_net_tx_packet(net);
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if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
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vhost_poll_queue(&vq->poll);
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