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| author | Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp> | 2018-07-03 09:31:33 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2018-07-04 14:30:46 +0200 |
| commit | be294a51adfc1e1d9884e34480c34e4388f27904 (patch) | |
| tree | f0f243eb398195ac71bc9f6b741aec7047d04171 /drivers/vhost | |
| parent | vhost_net: Avoid tx vring kicks during busyloop (diff) | |
| download | linux-be294a51adfc1e1d9884e34480c34e4388f27904.tar.xz linux-be294a51adfc1e1d9884e34480c34e4388f27904.zip | |
vhost_net: Avoid rx queue wake-ups during busypoll
We may run handle_rx() while rx work is queued. For example a packet can
push the rx work during the window before handle_rx calls
vhost_net_disable_vq().
In that case busypoll immediately exits due to vhost_has_work()
condition and enables vq again. This can lead to another unnecessary rx
wake-ups, so poll rx work instead of enabling the vq.
Signed-off-by: Toshiaki Makita <makita.toshiaki@lab.ntt.co.jp>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'drivers/vhost')
| -rw-r--r-- | drivers/vhost/net.c | 26 |
1 files changed, 19 insertions, 7 deletions
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c index 811c0e5ffc8e..791bc8b22aac 100644 --- a/drivers/vhost/net.c +++ b/drivers/vhost/net.c @@ -653,7 +653,8 @@ static void vhost_rx_signal_used(struct vhost_net_virtqueue *nvq) nvq->done_idx = 0; } -static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk) +static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk, + bool *busyloop_intr) { struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX]; struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX]; @@ -671,11 +672,16 @@ static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk) preempt_disable(); endtime = busy_clock() + tvq->busyloop_timeout; - while (vhost_can_busy_poll(endtime) && - !vhost_has_work(&net->dev) && - !sk_has_rx_data(sk) && - vhost_vq_avail_empty(&net->dev, tvq)) + while (vhost_can_busy_poll(endtime)) { + if (vhost_has_work(&net->dev)) { + *busyloop_intr = true; + break; + } + if (sk_has_rx_data(sk) || + !vhost_vq_avail_empty(&net->dev, tvq)) + break; cpu_relax(); + } preempt_enable(); @@ -795,6 +801,7 @@ static void handle_rx(struct vhost_net *net) s16 headcount; size_t vhost_hlen, sock_hlen; size_t vhost_len, sock_len; + bool busyloop_intr = false; struct socket *sock; struct iov_iter fixup; __virtio16 num_buffers; @@ -818,7 +825,9 @@ static void handle_rx(struct vhost_net *net) vq->log : NULL; mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF); - while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk))) { + while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk, + &busyloop_intr))) { + busyloop_intr = false; sock_len += sock_hlen; vhost_len = sock_len + vhost_hlen; headcount = get_rx_bufs(vq, vq->heads + nvq->done_idx, @@ -905,7 +914,10 @@ static void handle_rx(struct vhost_net *net) goto out; } } - vhost_net_enable_vq(net, vq); + if (unlikely(busyloop_intr)) + vhost_poll_queue(&vq->poll); + else + vhost_net_enable_vq(net, vq); out: vhost_rx_signal_used(nvq); mutex_unlock(&vq->mutex); |