Re: [PATCH v2 3/3] cpufreq: schedutil: map raw required frequency to driver frequency

From: Wanpeng Li
Date: Fri May 27 2016 - 01:41:19 EST

2016-05-26 10:53 GMT+08:00 Steve Muckle <steve.muckle@xxxxxxxxxx>:
> The slow-path frequency transition path is relatively expensive as it
> requires waking up a thread to do work. Should support be added for
> remote CPU cpufreq updates that is also expensive since it requires an
> IPI. These activities should be avoided if they are not necessary.
> To that end, calculate the actual driver-supported frequency required by
> the new utilization value in schedutil by using the recently added
> cpufreq_driver_resolve_freq callback. If it is the same as the
> previously requested driver frequency then there is no need to continue
> with the update assuming the cpu frequency limits have not changed. This
> will have additional benefits should the semantics of the rate limit be
> changed to apply solely to frequency transitions rather than to
> frequency calculations in schedutil.

sugov_should_update_freq() still be called before get_nex_freq() after
the patch applied, so rate limit still apply to both frequency
transitions and frequency calculations, right?

Wanpeng Li