Messages in this thread Patch in this message | | | From | Beata Michalska <> | Subject | [PATCH v3 3/3] arm64: Update AMU-based frequency scale factor on entering idle | Date | Tue, 12 Mar 2024 08:34:31 +0000 |
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Now that the frequency scale factor has been activated for retrieving current frequency on a given CPU, trigger its update upon entering idle. This will, to an extent, allow querying last known frequency in a non-invasive way. It will also improve the frequency scale factor accuracy when a CPU entering idle did not receive a tick for a while.
Suggested-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com> Signed-off-by: Beata Michalska <beata.michalska@arm.com> --- arch/arm64/kernel/topology.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 42cb19c31719..77c6ac577cef 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -215,6 +215,18 @@ static struct scale_freq_data amu_sfd = { .set_freq_scale = amu_scale_freq_tick, }; +void arch_cpu_idle_enter(void) +{ + unsigned int cpu = smp_processor_id(); + + if (!cpumask_test_cpu(cpu, amu_fie_cpus)) + return; + + /* Kick in AMU update but only if one has not happned already */ + if (time_is_before_jiffies(per_cpu(cpu_amu_samples.last_update, cpu))) + amu_scale_freq_tick(); +} + #define AMU_SAMPLE_EXP_MS 20 unsigned int arch_freq_get_on_cpu(int cpu) @@ -242,7 +254,8 @@ unsigned int arch_freq_get_on_cpu(int cpu) * try an alternative source for the counters (and thus freq scale), * if available for given policy */ - if (time_is_before_jiffies(last_update + msecs_to_jiffies(AMU_SAMPLE_EXP_MS))) { + if (!idle_cpu(cpu) && + time_is_before_jiffies(last_update + msecs_to_jiffies(AMU_SAMPLE_EXP_MS))) { struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); int ref_cpu = nr_cpu_ids; -- 2.25.1
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