On Wed, Feb 02, 2011 at 07:39:45AM -0800, Shirley Ma wrote: > On Wed, 2011-02-02 at 12:48 +0200, Michael S. Tsirkin wrote: > > Yes, I think doing this in the host is much simpler, > > just send an interrupt after there's a decent amount > > of space in the queue. > > > > Having said that the simple heuristic that I coded > > might be a bit too simple. > > >From the debugging out what I have seen so far (a single small message > TCP_STEAM test), I think the right approach is to patch both guest and > vhost.
One problem is slowing down the guest helps here. So there's a chance that just by adding complexity in guest driver we get a small improvement :( We can't rely on a patched guest anyway, so I think it is best to test guest and host changes separately. And I do agree something needs to be done in guest too, for example when vqs share an interrupt, we might invoke a callback when we see vq is not empty even though it's not requested. Probably should check interrupts enabled here? > The problem I have found is a regression for single small > message TCP_STEAM test. Old kernel works well for TCP_STREAM, only new > kernel has problem. Likely new kernel is faster :) > For Steven's problem, it's multiple stream TCP_RR issues, the old guest > doesn't perform well, so does new guest kernel. We tested reducing vhost > signaling patch before, it didn't help the performance at all. > > Thanks > Shirley Yes, it seems unrelated to tx interrupts. -- MST -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
