a bug on NO_HZ_FULL_ALL

[Frederic Weisbecker]

On Thu, Nov 14, 2013 at 01:39:43PM +0530, viresh kumar wrote:
> On Thursday 14 November 2013 01:35 PM, Vincent Guittot wrote:
> > AFAICT, It's a none issue. In full nohz, a timer fires periodically
> > (around 4sec period on ARM IIRC) on one cpu (cpu0).
> 
> Timer should always be running on CPU0, its out of nohz-full domain. Its
> cpu 1, where it will fire after long delays..
> 
> 
> https://wiki.linaro.org/WorkingGroups/PowerManagement/Doc/AdaptiveTickless

Right. CPU 0 stays pure periodic unless you select CONFIG_NO_HZ_FULL_SYSIDLE=y
then it can be also nohz when the full system is idle. I strongly recommend for power
consumption.