[PATCH v5 1/9] cpuidle: Add commonly used functionality for consolidation

[Rob Lee]

>
> I brought this topic up internally and Jon suggested that the 'usage'
> statistics that are reported in sysfs should also reflect failed
> versus successful C-state transitions, which is a great idea.  This
> could simply be achieved by renaming the current 'usage' count to
> something like 'transitions_attempted' and then conditionally
> increment a new counter within the 'if (entered_state >= 0)' block,
> perhaps named, 'transition_succeeded'.
>
> This way the old 'usage' count paradigm is as accurate as the new
> time-keeping code.  Being able to easily observe which C-state tend to
> fail the most would be invaluable in tuning idle policy for maximum
> effectiveness.
>
> Thoughts?

Sounds reasonable.  In some cases it may be helpful to track state
demotion as well.  Since I'm still a noob and wearing my submission
training wheels, I'm trying to minimize things that fall outside of
this basic consolidation effort for this patch series.  But I added
Jon's suggestion to this cpuidle page which contains future cpuidle
items to consider adding:
https://wiki.linaro.org/WorkingGroups/PowerManagement/Doc/CPUIdle#Track_both_attempted_and_successful_enter_attempts

>
> Regards,
> Mike
>
>>
>>>
>>> Regards,
>>> Mike