On Thu, Aug 30, 2012 at 09:20:57AM +0100, Richard Davies wrote: > Chris Webb wrote: > > I found that on my laptop, the single change of host kernel config > > > > -CONFIG_INTEL_IDLE=y > > +# CONFIG_INTEL_IDLE is not set > > > > is sufficient to turn transfers into guests from slow to full wire speed > > I am not deep enough in this code to write a patch, but I wonder if > macvtap_forward in macvtap.c is missing a call to kill_fasync, which I > understand is used to signal to interested processes when data arrives? >
No, only if TUN_FASYNC is set. qemu does not seem to set it. > Here is the end of macvtap_forward: > > skb_queue_tail(&q->sk.sk_receive_queue, skb); > wake_up_interruptible_poll(sk_sleep(&q->sk), POLLIN | POLLRDNORM | > POLLRDBAND); > return NET_RX_SUCCESS; > > > Compared to this end of tun_net_xmit in tun.c: > > /* Enqueue packet */ > skb_queue_tail(&tun->socket.sk->sk_receive_queue, skb); > > /* Notify and wake up reader process */ > if (tun->flags & TUN_FASYNC) > kill_fasync(&tun->fasync, SIGIO, POLL_IN); > wake_up_interruptible_poll(&tun->wq.wait, POLLIN | > POLLRDNORM | POLLRDBAND); > return NETDEV_TX_OK; > > > Richard.
