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

Arjan van de Ven
2010-10-25T16:00:17Z

On 10/25/2010 8:48 AM, Thomas Renninger wrote:
> On Monday 25 October 2010 16:56:04 Ingo Molnar wrote:
>> * Arjan van de Ven<arjan@linux.intel.com> wrote:
>>> On 10/25/2010 7:36 AM, Thomas Renninger wrote:
>>> ok so we have
>>>
>>> "C0 idle"
> Ideally this should not be called C0, but expressed
> as (#define) POLL_IDLE wherever possible.
>
> In all documentations/specs/white papers about other OSes
> C0 is refered to as not being idle.
> Linux mis-uses it as a self-defined idle state which
> is really confusing.

sure naming is one thing
>>> and
>>> "C0 no longer idle"
>>>
>>> I'd propose using the number 0 for the first one (it makes the most
>>> logical sense, it's the least deep idle state etc etc)
> I would use a special number for the "Linux only" state.

that special number is 0 though..
it makes sense in ordering, 0 < 1, 1 < 2 etc

0 makes for a really bad special number for the exit marker; not just here,
but also for your suspend hook, that one definitely needs to change
(since current commercially available SOCs already reuse 0 for this for
standby level states)