Re: [PATCH] sched/fair: Only apply cpufreq pressure where frequency is invariant

[Vincent Guittot]

On Wed, 9 Sept 2026 at 12:05, K Prateek Nayak <kprateek.nayak@xxxxxxx> wrote:
>
> Hello Hongyan,
>
> On 9/9/2026 9:39 AM, Hongyan Xia wrote:
> >> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> >> index b898b6544069..97f4a3ba5107 100644
> >> --- a/drivers/cpufreq/cpufreq.c
> >> +++ b/drivers/cpufreq/cpufreq.c
> >> @@ -2586,8 +2586,11 @@ static void cpufreq_update_pressure(struct cpufreq_policy *policy)
> >>
> >>      cpu = cpumask_first(policy->related_cpus);
> >>      max_freq = arch_scale_freq_ref(cpu);
> >> -    if (!max_freq)
> >> -            max_freq = policy->cpuinfo.max_freq;
> >> +    if (!max_freq) {
> >> +            max_freq = __resolve_freq(policy, policy->cpuinfo.max_freq,
> >> +                                      policy->cpuinfo.min_freq, policy->cpuinfo.max_freq,
> >> +                                      CPUFREQ_RELATION_H);

As long as the reference frequency used in cpufreq_update_pressure
remains fixed whetever boost is enabled or not this is ok. We don't
want the pressure to change when boost is enabled or disabled only
when policy->max changes.

> >> +    }
> >>
> >>      capped_freq = policy->max;
> >>
> >
> > LGTM.
>
> Thanks a ton for taking a look at the suggestion.
>
> >
> > NIT: I do wonder if we need a full __resolve_freq() each time. We could
> > cache the highest achievable OPP on max_freq updates, but that's future
> > optimization.
>
> Sure! We can cache it in the policy object during
> cpufreq_policy_online().
>
> Jianyong Wu would like to take a stab at it? If not, I can send it out
> early next week.
>
> --
> Thanks and Regards,
> Prateek
>
> Disclaimer: Hygon emails are routed differently in our organization.
> Response might be slightly delayed until my NNTP rule finds the email.
> Sorry for any inconvenience.