Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit c92112ae authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
Browse files

vhost_net: use vhost_add_used_and_signal_n() in vhost_zerocopy_signal_used() 



We tend to batch the used adding and signaling in vhost_zerocopy_callback()
which may result more than 100 used buffers to be updated in
vhost_zerocopy_signal_used() in some cases. So switch to use
vhost_add_used_and_signal_n() to avoid multiple calls to
vhost_add_used_and_signal(). Which means much less times of used index
updating and memory barriers.

2% performance improvement were seen on netperf TCP_RR test.

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 094afe7d

drivers/vhost/net.c

+8 −5
Original line number Diff line number Diff line
@@ -281,7 +281,7 @@ static void vhost_zerocopy_signal_used(struct vhost_net *net, 
{

	struct vhost_net_virtqueue *nvq =

		container_of(vq, struct vhost_net_virtqueue, vq);

	int i;

	int i, add;

	int j = 0;



	for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
@@ -289,14 +289,17 @@ static void vhost_zerocopy_signal_used(struct vhost_net *net, 
			vhost_net_tx_err(net);

		if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {

			vq->heads[i].len = VHOST_DMA_CLEAR_LEN;

			vhost_add_used_and_signal(vq->dev, vq,

						  vq->heads[i].id, 0);

			++j;

		} else

			break;

	}

	if (j)

		nvq->done_idx = i;

	while (j) {

		add = min(UIO_MAXIOV - nvq->done_idx, j);

		vhost_add_used_and_signal_n(vq->dev, vq,

					    &vq->heads[nvq->done_idx], add);

		nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;

		j -= add;

	}

}



static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)