On 12/10/2016 17:27, Greg wrote: >> > > Yes, you're partially right. > I've done some tests on how reduce interrupt latency. Using idle=poll or > use stress tests in guest permit to reduce half the latency (but is a > real hog on host :/). > Using "intel_idle.max_cstate=0 processor.max_cstate=0 idle=poll" on host > permits to get the same result (without cpu hog) > > In conclusion, I get with theses results : ~120µs between guest (from > 180µs previously). > > Running iperf with these new modifications still get better results with > ~60µs (a third from the initial value, half from idle=poll value). > > Is there something else I can eventually tune ? With a real workload, you might be able to get the same performance as idle=poll thanks to KVM's automatic polling for interrupts. As long as packets are delivered within 400 microseconds, and only if there is no other active process on the host's CPU, KVM will poll for guest interrupts instead of putting the guest's CPU to sleep. This of course doesn't trigger for ping, which only wakes up the guest once per second. Paolo -- 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
