On Wed, 21 Jan 2009, Avi Kivity wrote: > Kevin Shanahan wrote: > > > > --- hermes-old.wumi.org.au ping statistics --- > > > > 900 packets transmitted, 900 received, 0% packet loss, time 899326ms > > > > rtt min/avg/max/mdev = 0.093/0.157/3.611/0.117 ms > > > > > > > > So, a _huge_ difference. But what does it mean? > > > > > > > It means, a scheduling problem. Can you run the latency tracer (which > > > only works with realtime priority), so we can tell if it is (a) kvm > > > failing to wake up the vcpu properly or (b) the scheduler delaying the > > > vcpu from running. > > > > > > > Sorry, but are you sure that's going to be useful? > > > > If it only works on realtime threads and I'm not seeing the problem when > > running kvm with realtime priority, is this going to tell you what you > > want to know? > > > > Not trying to be difficult, but that just didn't make sense to me. > > > > You're right, wasn't thinking properly. > > This is a tough one. I'll see if I can think of something. Ingo, any ideas? > I should have replied to this email :-) Yeah, I'm working on making wakeup latency tracer work with non rt tasks. The "wakeup" tracer will now trace all tasks where as a new "wakeup_rt" tracer will only trace rt tasks. I did it for rt tasks only because it only records the highest latency wake ups and the non rt tasks were always bigger than the rt tasks which made what I was tracing useless (the rt scheduling). But by not having an option for all tasks, it makes the wakeup tracer useless for everyone else ;-) -- Steve -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
