virtio: orphan skbs if we're relying on timer to free them We check for finished xmit skbs on every xmit, or on a timer (unless the host promises to force an interrupt when the xmit ring is empty). This can penalize userspace tasks which fill their sockbuf. There are a finite number of packets which can be in the transmission queue. We could fire the timer more than every 100ms, but that would just hurt performance for a corner case. This seems neatest. Signed-off-by: Rusty Russell --- drivers/net/virtio_net.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -522,6 +522,11 @@ static int start_xmit(struct sk_buff *sk { struct virtnet_info *vi = netdev_priv(dev); + /* We queue a limited number; don't let that delay writers if + * we are slow in getting tx interrupt. */ + if (!vi->free_in_tasklet) + skb_orphan(skb); + again: /* Free up any pending old buffers before queueing new ones. */ free_old_xmit_skbs(vi);