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

Turquette, Mike mturquette at ti.com
Tue Feb 28 23:47:14 UTC 2012

On Tue, Feb 28, 2012 at 3:33 PM, Rob Lee <rob.lee at linaro.org> wrote:
>> 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

Yeah, I don't want to feature-bloat your submission more than
necessary.  I'm happy for the usage counter stuff to get tackled at a
later date, but you're still on board for setting last_residency to
zero in this series, right?


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

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