Messages in this thread Patch in this message | | | From | Beata Michalska <> | Subject | [PATCH v5 4/5] arm64: Update AMU-based frequency scale factor on entering idle | Date | Wed, 17 Apr 2024 10:38:47 +0100 |
| |
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 475fdbf3032a..3110863ee18c 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -213,6 +213,19 @@ static __always_inline bool amu_fie_cpu_supported(unsigned int cpu) cpumask_test_cpu(cpu, amu_fie_cpus); } +void arch_cpu_idle_enter(void) +{ + unsigned int cpu = smp_processor_id(); + + if (!amu_fie_cpu_supported(cpu)) + 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) @@ -239,8 +252,8 @@ 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
| |