Re: [PATCH 2/3] cpufreq: Avoid redundant target() calls for unchanged limits

[Viresh Kumar]

On 21-05-26, 21:58, Zhongqiu Han wrote:
> > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
> > index 1292da53e5fc..7f19ec6b70ba 100644
> > --- a/drivers/cpufreq/intel_pstate.c
> > +++ b/drivers/cpufreq/intel_pstate.c
> > @@ -2942,6 +2942,7 @@ static void intel_pstate_adjust_policy_max(struct cpudata *cpu,
> >   	    policy->max > cpu->pstate.max_freq) {
> >   		pr_debug("policy->max > max non turbo frequency\n");
> >   		policy->max = policy->cpuinfo.max_freq;
> > +		policy->update_limits = true;
> 
> 
> Could this be redundant?

Yeah, this won't even compile I think. In my first attempt I tried to
make the update_limits change from within verify in cpufreq.h and that
caused a build failure and then I moved to cpufreq_set_policy() and
forgot to fix this one. And my arm64 build didn't cover this file.
Sorry about that.

> It seems that intel_pstate_adjust_policy_max() is only triggered when
> !hwp_active, whereas CPUFREQ_NEED_UPDATE_LIMITS is set when
> hwp_active is enabled. If so, the update_limits flag set here may not
> actually be consumed, as __cpufreq_driver_target() would skip the
> update_limits check for drivers without CPUFREQ_NEED_UPDATE_LIMITS.

Good catch.

Rafael, is the understanding correct ? I can drop the intel_pstate
change in that case.

-- 
viresh