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vhost_net: stop polling socket during rx processing

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We don't stop rx polling socket during rx processing, this will lead
unnecessary wakeups from under layer net devices (E.g
sock_def_readable() form tun). Rx will be slowed down in this
way. This patch avoids this by stop polling socket during rx
processing. A small drawback is that this introduces some overheads in
light load case because of the extra start/stop polling, but single
netperf TCP_RR does not notice any change. In a super heavy load case,
e.g using pktgen to inject packet to guest, we get about ~8.8%
improvement on pps:

before: ~1240000 pkt/s
after:  ~1350000 pkt/s

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>
This commit is contained in:
Jason Wang 2016-06-01 01:56:33 -04:00 committed by David S. Miller
parent aaa76724d7
commit 8241a1e466
1 changed files with 33 additions and 31 deletions
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64
drivers/vhost/net.c
View File

@ -301,6 +301,32 @@ static bool vhost_can_busy_poll(struct vhost_dev *dev,
!vhost_has_work(dev);
}
static void vhost_net_disable_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{
struct vhost_net_virtqueue *nvq =
container_of(vq, struct vhost_net_virtqueue, vq);
struct vhost_poll *poll = n->poll + (nvq - n->vqs);
if (!vq->private_data)
return;
vhost_poll_stop(poll);
}
static int vhost_net_enable_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{
struct vhost_net_virtqueue *nvq =
container_of(vq, struct vhost_net_virtqueue, vq);
struct vhost_poll *poll = n->poll + (nvq - n->vqs);
struct socket *sock;
sock = vq->private_data;
if (!sock)
return 0;
return vhost_poll_start(poll, sock->file);
}
static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
struct vhost_virtqueue *vq,
struct iovec iov[], unsigned int iov_size,
@ -613,6 +639,7 @@ static void handle_rx(struct vhost_net *net)
if (!sock)
goto out;
vhost_disable_notify(&net->dev, vq);
vhost_net_disable_vq(net, vq);
vhost_hlen = nvq->vhost_hlen;
sock_hlen = nvq->sock_hlen;
@ -629,7 +656,7 @@ static void handle_rx(struct vhost_net *net)
likely(mergeable) ? UIO_MAXIOV : 1);
/* On error, stop handling until the next kick. */
if (unlikely(headcount < 0))
break;
goto out;
/* On overrun, truncate and discard */
if (unlikely(headcount > UIO_MAXIOV)) {
iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
@ -648,7 +675,7 @@ static void handle_rx(struct vhost_net *net)
}
/* Nothing new? Wait for eventfd to tell us
* they refilled. */
break;
goto out;
}
/* We don't need to be notified again. */
iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
@ -676,7 +703,7 @@ static void handle_rx(struct vhost_net *net)
&fixup) != sizeof(hdr)) {
vq_err(vq, "Unable to write vnet_hdr "
"at addr %p\n", vq->iov->iov_base);
break;
goto out;
}
} else {
/* Header came from socket; we'll need to patch
@ -692,7 +719,7 @@ static void handle_rx(struct vhost_net *net)
&fixup) != sizeof num_buffers) {
vq_err(vq, "Failed num_buffers write");
vhost_discard_vq_desc(vq, headcount);
break;
goto out;
}
vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
headcount);
@ -701,9 +728,10 @@ static void handle_rx(struct vhost_net *net)
total_len += vhost_len;
if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
vhost_poll_queue(&vq->poll);
break;
goto out;
}
}
vhost_net_enable_vq(net, vq);
out:
mutex_unlock(&vq->mutex);
}
@ -782,32 +810,6 @@ static int vhost_net_open(struct inode *inode, struct file *f)
return 0;
}
static void vhost_net_disable_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{
struct vhost_net_virtqueue *nvq =
container_of(vq, struct vhost_net_virtqueue, vq);
struct vhost_poll *poll = n->poll + (nvq - n->vqs);
if (!vq->private_data)
return;
vhost_poll_stop(poll);
}
static int vhost_net_enable_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{
struct vhost_net_virtqueue *nvq =
container_of(vq, struct vhost_net_virtqueue, vq);
struct vhost_poll *poll = n->poll + (nvq - n->vqs);
struct socket *sock;
sock = vq->private_data;
if (!sock)
return 0;
return vhost_poll_start(poll, sock->file);
}
static struct socket *vhost_net_stop_vq(struct vhost_net *n,
struct vhost_virtqueue *vq)
{