On 2018年07月04日 09:21, Toshiaki Makita wrote:
On 2018/07/03 18:05, Jason Wang wrote:
On 2018年07月03日 15:31, Toshiaki Makita wrote:
We may run out of avail rx ring descriptor under heavy load but busypoll
did not detect it so busypoll may have exited prematurely. Avoid this by
checking rx ring full during busypoll.
Actually, we're checking whether it was empty in fact?
My understanding is that on rx empty avail means no free descriptors
from the perspective of host so the ring is conceptually full.
Ok.
Signed-off-by: Toshiaki Makita <makita.toshiaki@xxxxxxxxxxxxx>
---
drivers/vhost/net.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 791bc8b..b224036 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -658,6 +658,7 @@ static int vhost_net_rx_peek_head_len(struct
vhost_net *net, struct sock *sk,
{
struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX];
+ struct vhost_virtqueue *rvq = &rnvq->vq;
struct vhost_virtqueue *tvq = &tnvq->vq;
unsigned long uninitialized_var(endtime);
int len = peek_head_len(rnvq, sk);
@@ -677,7 +678,8 @@ static int vhost_net_rx_peek_head_len(struct
vhost_net *net, struct sock *sk,
*busyloop_intr = true;
break;
}
- if (sk_has_rx_data(sk) ||
+ if ((sk_has_rx_data(sk) &&
+ !vhost_vq_avail_empty(&net->dev, rvq)) ||
!vhost_vq_avail_empty(&net->dev, tvq))
break;
cpu_relax();
@@ -827,7 +829,6 @@ static void handle_rx(struct vhost_net *net)
I thought below codes should belong to patch 3. Or I may miss something.
That codes are added for the case that busypoll is waiting for rx vq
avail but interrupted by another work. At the point of patch 3 busypoll
does not wait for rx vq avail so I don't think we move them to patch 3.
I get this.
Thanks
Thanks
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,
@@ -838,7 +839,9 @@ static void handle_rx(struct vhost_net *net)
goto out;
/* OK, now we need to know about added descriptors. */
if (!headcount) {
- if (unlikely(vhost_enable_notify(&net->dev, vq))) {
+ if (unlikely(busyloop_intr)) {
+ vhost_poll_queue(&vq->poll);
+ } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
/* They have slipped one in as we were
* doing that: check again. */
vhost_disable_notify(&net->dev, vq);
@@ -848,6 +851,7 @@ static void handle_rx(struct vhost_net *net)
* they refilled. */
goto out;
}
+ busyloop_intr = false;
if (nvq->rx_ring)
msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
/* On overrun, truncate and discard */
