On 2019/4/10 下午9:42, Toke Høiland-Jørgensen wrote:
Jason Wang <jasow...@redhat.com> writes:
On 2019/4/10 下午9:01, David Woodhouse wrote:
On Wed, 2019-04-10 at 15:01 +0300, David Woodhouse wrote:
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1125,7 +1128,9 @@ static netdev_tx_t tun_net_xmit(struct sk_buff
*skb, struct net_device *dev)
if (tfile->flags & TUN_FASYNC)
kill_fasync(&tfile->fasync, SIGIO, POLL_IN);
tfile->socket.sk->sk_data_ready(tfile->socket.sk);
+ if (!ptr_ring_empty(&tfile->tx_ring))
+ netif_stop_queue(tun->dev);
rcu_read_unlock();
return NETDEV_TX_OK;
Hm, that should be using ptr_ring_full() shouldn't it? So...
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1121,6 +1121,9 @@ static netdev_tx_t tun_net_xmit(struct s
if (ptr_ring_produce(&tfile->tx_ring, skb))
goto drop;
+ if (ptr_ring_full(&tfile->tx_ring))
+ netif_stop_queue(tun->dev);
+
/* Notify and wake up reader process */
if (tfile->flags & TUN_FASYNC)
kill_fasync(&tfile->fasync, SIGIO, POLL_IN);
@@ -2229,6 +2232,7 @@ static ssize_t tun_do_read(struct tun_st
consume_skb(skb);
}
+ netif_wake_queue(tun->dev);
return ret;
}
That doesn't seem to make much difference at all; it's still dropping a
lot of packets because ptr_ring_produce() is returning non-zero.
I think you need try to stop the queue just in this case? Ideally we may
want to stop the queue when the queue is about to full, but we don't
have such helper currently.
Ideally we want to react when the queue starts building rather than when
it starts getting full; by pushing back on upper layers (or, if
forwarding, dropping packets to signal congestion).
In practice, this means tuning the TX ring to the *minimum* size it can
be without starving (this is basically what BQL does for Ethernet), and
keeping packets queued in the qdisc layer instead, where it can be
managed...
-Toke
Yes, but we do have user that don't use qdisc at all.
Thanks
