[PATCH v2 4/6] cpufreq/schedutil: use a fixed reference frequency
From: Vincent Guittot <vincent.guittot@linaro.org>
Date: 2023-10-09 10:36:47
Also in:
linux-pm, linux-riscv, lkml
Subsystem:
cpu frequency scaling framework, scheduler, the rest · Maintainers:
"Rafael J. Wysocki", Viresh Kumar, Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
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> --- kernel/sched/cpufreq_schedutil.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-)
diff --git a/kernel/sched/cpufreq_schedutil.c b/kernel/sched/cpufreq_schedutil.c
index 4492608b7d7f..1fa7e74add8f 100644
--- a/kernel/sched/cpufreq_schedutil.c
+++ b/kernel/sched/cpufreq_schedutil.c@@ -114,6 +114,28 @@ static void sugov_deferred_update(struct sugov_policy *sg_policy) } } +/** + * cpufreq_get_capacity_ref_freq - get the reference frequency of a given CPU that + * has been used to correlate frequency and compute capacity. + * @policy: the cpufreq policy of the CPU in question. + * @use_current: Fallback to current freq instead of policy->cpuinfo.max_freq. + * + * 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.
@@ -140,10 +162,10 @@ static unsigned int get_next_freq(struct sugov_policy *sg_policy, 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; util = map_util_perf(util); + 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)
--
2.34.1
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