On 2018年03月27日 17:12, haibinzhang(张海斌) wrote:
handle_tx() will delay rx for a long time when busy tx polling udp packets
with short length(ie: 1byte udp payload), because setting VHOST_NET_WEIGHT
takes into account only sent-bytes but no time.
Interesting.
Looking at vhost_can_busy_poll() it tries to poke pending vhost work and
exit the busy loop if it found one. So I believe something block the
work queuing. E.g did reverting 8241a1e466cd56e6c10472cac9c1ad4e54bc65db
fix the issue?
It's not fair for handle_rx(),
so needs to limit max time of tx polling.
Signed-off-by: Haibin Zhang <haibinzhang@xxxxxxxxxxx>
---
drivers/vhost/net.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 8139bc70ad7d..dc9218a3a75b 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -473,6 +473,7 @@ static void handle_tx(struct vhost_net *net)
struct socket *sock;
struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
bool zcopy, zcopy_used;
+ unsigned long start = jiffies;
Checking jiffies is tricky, need to convert it to ms or whatever others.
mutex_lock(&vq->mutex);
sock = vq->private_data;
@@ -580,7 +581,7 @@ static void handle_tx(struct vhost_net *net)
else
vhost_zerocopy_signal_used(net, vq);
vhost_net_tx_packet(net);
- if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
+ if (unlikely(total_len >= VHOST_NET_WEIGHT) || unlikely(jiffies - start >= 1)) {
How value 1 is determined here? And we need a complete test to make sure
this won't affect other use cases.
Another thought is introduce another limit of #packets, but this need
benchmark too.
Thanks
vhost_poll_queue(&vq->poll);
break;
}
