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authorJason Wang <jasowang@redhat.com>2016-06-01 01:56:33 -0400
committerDavid S. Miller <davem@davemloft.net>2016-06-07 14:46:11 -0700
commit8241a1e466cd56e6c10472cac9c1ad4e54bc65db (patch)
tree974e57de809b0262a7a131a9494a4d8dfec33b3e /drivers/vhost
parentaaa76724d7ece87eb5f66e02fac9da036dd20667 (diff)
vhost_net: stop polling socket during rx processing
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>
Diffstat (limited to 'drivers/vhost')
-rw-r--r--drivers/vhost/net.c64
1 files changed, 33 insertions, 31 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f744eeb3e2b4..1d3e45f84549 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -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)
{