| Message ID | 1464760594-30326-2-git-send-email-jasowang@redhat.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Wed, Jun 01, 2016 at 01:56:33AM -0400, Jason Wang wrote: > 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> I guess this works though I suspect it's even faster to maintain some state in the vq structure so we don't need to play with waitq all the time. For now Acked-by: Michael S. Tsirkin <mst@redhat.com> > --- > drivers/vhost/net.c | 64 +++++++++++++++++++++++++++-------------------------- > 1 file changed, 33 insertions(+), 31 deletions(-) > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > index f744eeb..1d3e45f 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) > { > -- > 1.8.3.1
From: Jason Wang <jasowang@redhat.com> Date: Wed, 1 Jun 2016 01:56:33 -0400 > 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> Applied.
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index f744eeb..1d3e45f 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) {
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> --- drivers/vhost/net.c | 64 +++++++++++++++++++++++++++-------------------------- 1 file changed, 33 insertions(+), 31 deletions(-)