On 2106.034.01 10:45 Srinivas Pandruvada wrote: > On Fri, 2016-04-01 at 16:06 +0200, Jörg Otte wrote: > > > > > > >> Done. Attached the tracer. >> For me it looks like the previous one of the failing case. > > The traces show that idle task is constantly running without sleep.
No, they (at least the first one, I didn't look at the next one yet) show that CPUs 2 and 3 are spending around 99% of their time not in state C0. That the sample rate is ending up at ~10 Milliseconds, indicates some high frequency (>= 100Hz) events on those CPUs. Those events, apparently, take very little CPU time to complete, hence a load of about 1% on average. By the way, I can recreate the high sample rate with virtually no load on my system easy, but so far have been unable to get the high CPU frequencies observed by Jörg. I can get my system to about a target pstate of 20 where it should have remained at 16, but that is about it. > The driver is processing samples for idle task for every 10ms and > aperf/mperf are showing that we are always in turbo mode for idle task. That column pretty much always says "idle" (or swapper for my way of doing things). I have not found it to very useful as an indicator, and considerably more so since the utilization changes. > > Need to find out why idle task is not sleeping. I contend that is it. I don't have enough reverted data, but so far this seems very much like that bug report I referenced earlier. ... Doug
