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

Viresh Kumar
2020-12-15T04:18:16Z

On 14-12-20, 21:01, Rafael J. Wysocki wrote:
> 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.

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

--
viresh