> On Tue, 2011-02-01 at 22:05 -0800, Shirley Ma wrote: > > > > The way I am changing is only when netif queue has stopped, then we > > start to count num_free descriptors to send the signal to wake netif > > queue. > > I forgot to mention, the code change I am making is in guest kernel, in > xmit call back only wake up the queue when it's stopped && num_free >= > 1/2 *vq->num, I add a new API in virtio_ring. FYI :) I have tried this before. There are a couple of issues: 1. the free count will not reduce until you run free_old_xmit_skbs, which will not run anymore since the tx queue is stopped. 2. You cannot call free_old_xmit_skbs directly as it races with a queue that was just awakened (current cb was due to the delay in disabling cb's). You have to call free_old_xmit_skbs() under netif_queue_stopped() check to avoid the race. I got a small improvement in my testing upto some number of threads (32 or 48?), but beyond that I was getting a regression. Thanks, - KK > However vhost signaling reduction is needed as well. The patch I > submitted a while ago showed both CPUs and BW improvement. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
