Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | From | Beata Michalska <> | Subject | [PATCH v4 3/4] arm64: Update AMU-based frequency scale factor on entering idle | Date | Fri, 5 Apr 2024 14:33:18 +0100 |
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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. As a consequence, for idle cores, the reported frequency will be the last one observed before entering the idle state.
Suggested-by: Vanshidhar Konda <vanshikonda@os.amperecomputing.com> Signed-off-by: Beata Michalska <beata.michalska@arm.com> --- arch/arm64/kernel/topology.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index b03fe8617721..f204f6489f98 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -207,6 +207,19 @@ 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 happened already */ + if (housekeeping_cpu(cpu, HK_TYPE_TICK) && + 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) @@ -232,8 +245,8 @@ unsigned int arch_freq_get_on_cpu(int cpu) * this boils down to identifying an active cpu within the same freq * domain, if any. */ - if (!housekeeping_cpu(cpu, HK_TYPE_TICK) || - time_is_before_jiffies(last_update + msecs_to_jiffies(AMU_SAMPLE_EXP_MS))) { + if (!housekeeping_cpu(cpu, HK_TYPE_TICK) || (!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 = cpu; -- 2.25.1
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