Re: [PATCH 2/3] PERF(kernel): Cleanup power events

Arjan van de Ven
2010-10-25T14:11:10Z

On 10/25/2010 5:55 AM, Thomas Renninger wrote:

>> But the actual code does not actually deal with any 'state 0', does it?
> It does. Not being idle is tracked by cpuidle driver as state 0
> (arch independent):
> /sys/devices/system/cpu/cpu0/cpuidle/state0/
> halt/C1 on X86 is:
> /sys/devices/system/cpu/cpu0/cpuidle/state1/
> ...
state0 is still OS idle!

the API is just weird for this, from a userspace perspective

if the kernel picks this state 0 for the idle handler, the userspace app
gets
two events

one for going to state 0 to enter the idle state
one for going to state 0 to exit idle

but they're the exact same event in your API.

rather unpleasant from a userspace program perspective....
now I need to start tracking even more state on top in powertop to be
able to make a guess at which of the two meanings a state 0 entry has.