6.6-stable review patch. If anyone has any objections, please let me know.
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From: Vincent Guittot vincent.guittot@linaro.org
commit b3edde44e5d4504c23a176819865cd603fd16d6c upstream.
cpuinfo.max_freq can change at runtime because of boost as an example. This implies that the value could be different than the one that has been used when computing the capacity of a CPU.
The new arch_scale_freq_ref() returns a fixed and coherent reference frequency that can be used when computing a frequency based on utilization.
Use this arch_scale_freq_ref() when available and fallback to policy otherwise.
Signed-off-by: Vincent Guittot vincent.guittot@linaro.org Signed-off-by: Ingo Molnar mingo@kernel.org Tested-by: Lukasz Luba lukasz.luba@arm.com Reviewed-by: Lukasz Luba lukasz.luba@arm.com Reviewed-by: Dietmar Eggemann dietmar.eggemann@arm.com Acked-by: Rafael J. Wysocki rafael@kernel.org Acked-by: Viresh Kumar viresh.kumar@linaro.org Link: https://lore.kernel.org/r/20231211104855.558096-4-vincent.guittot@linaro.org Stable-dep-of: e37617c8e53a ("sched/fair: Fix frequency selection for non-invariant case") Signed-off-by: Wentao Guan guanwentao@uniontech.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/sched/cpufreq_schedutil.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-)
--- a/kernel/sched/cpufreq_schedutil.c +++ b/kernel/sched/cpufreq_schedutil.c @@ -138,6 +138,28 @@ static void sugov_deferred_update(struct }
/** + * get_capacity_ref_freq - get the reference frequency that has been used to + * correlate frequency and compute capacity for a given cpufreq policy. We use + * the CPU managing it for the arch_scale_freq_ref() call in the function. + * @policy: the cpufreq policy of the CPU in question. + * + * Return: the reference CPU frequency to compute a capacity. + */ +static __always_inline +unsigned long get_capacity_ref_freq(struct cpufreq_policy *policy) +{ + unsigned int freq = arch_scale_freq_ref(policy->cpu); + + if (freq) + return freq; + + if (arch_scale_freq_invariant()) + return policy->cpuinfo.max_freq; + + return policy->cur; +} + +/** * get_next_freq - Compute a new frequency for a given cpufreq policy. * @sg_policy: schedutil policy object to compute the new frequency for. * @util: Current CPU utilization. @@ -163,9 +185,9 @@ static unsigned int get_next_freq(struct unsigned long util, unsigned long max) { struct cpufreq_policy *policy = sg_policy->policy; - unsigned int freq = arch_scale_freq_invariant() ? - policy->cpuinfo.max_freq : policy->cur; + unsigned int freq;
+ freq = get_capacity_ref_freq(policy); freq = map_util_freq(util, freq, max);
if (freq == sg_policy->cached_raw_freq && !sg_policy->need_freq_update)