On Tue, Feb 01, 2011 at 11:14:51PM -0800, Shirley Ma wrote: > On Wed, 2011-02-02 at 08:29 +0200, Michael S. Tsirkin wrote: > > On Tue, Feb 01, 2011 at 10:19:09PM -0800, Shirley Ma wrote: > > > 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. > > > > Interesting. Yes, I agree an API extension would be helpful. However, > > wouldn't just the signaling reduction be enough, without guest > > changes? > > w/i guest change, I played around the parameters,for example: I could > get 3.7Gb/s with 42% CPU BW increasing from 2.5Gb/s for 1K message size, > w/i dropping packet, I was able to get up to 6.2Gb/s with similar CPU > usage. We need to consider them separately IMO. What's the best we can get without guest change? And which parameters give it? There will always be old guests, and as far as I can tell it should work better from host. > > > However vhost signaling reduction is needed as well. The patch I > > > submitted a while ago showed both CPUs and BW improvement. > > > > > > Thanks > > > Shirley > > > > Which patch was that? > > The patch was called "vhost: TX used buffer guest signal accumulation". Yes, a somewhat similar idea. > You suggested to split add_used_bufs and signal. Exactly. And this is basically what this patch does. > I am still thinking > what's the best approach to cooperate guest (virtio_kick) and > vhost(handle_tx), vhost(signaling) and guest (xmit callback) to reduce > the overheads, so I haven't submit the new patch yet. > > Thanks > Shirley -- MST -- 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
