Re: [PATCH v2 02/10] cpufreq: provide data for frequency-invariant load-tracking support

From: Dietmar Eggemann
Date: Tue Jul 11 2017 - 11:13:06 EST

On 11/07/17 15:59, Rafael J. Wysocki wrote:
> On Tuesday, July 11, 2017 04:06:01 PM Dietmar Eggemann wrote:
>> On 11/07/17 07:01, Viresh Kumar wrote:
>>> On 10-07-17, 13:02, Dietmar Eggemann wrote:
>>>> Yes, I will change this. The #define approach is not really necessary
>>>> here since we're not in the scheduler hot-path and inlining is not
>>>> really required here.
>>> It would be part of scheduler hot-path for the fast-switching case, isn't it ?
>>> (I am not arguing against using weak functions, just wanted to correct above
>>> statement).
>> Yes you're right here.
>> But in the meantime we're convinced that cpufreq_driver_fast_switch() is
>> not the right place to call arch_set_freq_scale() since for (future)
>> arm/arm64 fast-switch driver, the return value of
>> cpufreq_driver->fast_switch() does not give us the information that the
>> frequency value did actually change.
>> So we probably have to do this soemwhere in the cpufreq driver(s) to
>> support fast-switching until we have aperf/mperf like counters.
> If that's the case, I'd say call arch_set_freq_scale() from drivers in all
> cases or it will get *really* confusing.

Agreed, we should do it for slow-switching drivers from within the
driver as well in this case.