[PATCH v2 0/3] cpufreq: Allow drivers to receive more information from the governor

Rafael J. Wysocki
2020-12-14T20:11:45Z

Hi,

The timing of this is not perfect (sorry about that), but here's a refresh
of this series.

The majority of the previous cover letter still applies:

On Monday, December 7, 2020 5:25:38 PM CET Rafael J. Wysocki wrote:
>
> This is based on the RFC posted a few days ago:
>
> https://lore.kernel.org/linux-pm/1817571.2o5Kk4Ohv2@kreacher/
>
> Using intel_pstate in the passive mode with HWP enabled, in particular under
> the schedutil governor, is still kind of problematic, because it has to assume
> that it should not allow the frequency to fall below the one requested by the
> governor. For this reason, it translates the target frequency into HWP.REQ.MIN
> which generally causes the processor to run a bit too fast.
>
> Moreover, this allows the HWP algorithm to use any frequency between the target
> one and HWP.REQ.MAX that corresponds to the policy max limit and some workloads
> cause it to go for the max turbo frequency prematurely which hurts energy-
> efficiency without improving performance, even though the schedutil governor
> itself would not allow the frequency to ramp up so fast.
>
> This patch series attempts to improve the situation by introducing a new driver
> callback allowing the driver to receive more information from the governor. In
> particular, this allows the min (required) and target (desired) performance
> levels to be passed to it and those can be used to give better hints to the
> hardware.

In this second revision there are three patches (one preparatory patch for
schedutil that hasn't changed since the v1, the introduction of the new
callback and schedutil changes in patch [2/3] and the intel_pstate changes
in patch [3/3] that are the same as before.

Please see patch changelogs for details.

Thanks!