On Thu, Nov 26, 2015 at 06:34:45PM +0000, Nuno Gonçalves wrote:
> I'm still collecting data to be more sure. But it looks for now:
> 
> 1 - nohz=off does not have any effect.

Can you confirm the rate at which the LOC counter in /proc/interrupts
is increasing on an idle machine doesn't change with nohz=off?

> 2 - With a kernel without Dynamic ticks enabled the latencies are
> actually always greater, and they increase with system load! They
> still decrease if I have a periodic thread waking very frequently.
> 
> That is: Threads waking regularly and for short intervals decrease
> latency. Threads waking infrequently but doing a log of work increase
> latency.

That's interesting. Is it possible that it affects only the PPS
capture somehow?

> I will share some annotated plots in a few days to make this very
> clear. Anyway do you have any idea what can be happening here? Maybe
> some cpuidle states are being entered despite being disabled?

No idea.

-- 
Miroslav Lichvar

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