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

On Wed, 9 Sept 2026 at 12:05, K Prateek Nayak [off-list ref] wrote:

Hello Hongyan,

On 9/9/2026 9:39 AM, Hongyan Xia wrote:

quoted

quoted

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.

quoted

quoted

+    }

     capped_freq = policy->max;

LGTM.

Thanks a ton for taking a look at the suggestion.

quoted

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.