Commit 39b19974 authored by Beata Michalska's avatar Beata Michalska Committed by Catalin Marinas
Browse files

arm64: Update AMU-based freq scale factor on entering idle 



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: default avatarVanshidhar Konda <vanshikonda@os.amperecomputing.com>
Signed-off-by: default avatarBeata Michalska <beata.michalska@arm.com>
Reviewed-by: default avatarPrasanna Kumar T S M <ptsm@linux.microsoft.com>
Reviewed-by: default avatarSumit Gupta <sumitg@nvidia.com>
Link: https://lore.kernel.org/r/20250131162439.3843071-5-beata.michalska@arm.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 16d1e274

arch/arm64/kernel/topology.c

+13 −0
Original line number Diff line number Diff line
@@ -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_scale_update, cpu)))

		amu_scale_freq_tick();

}



#define AMU_SAMPLE_EXP_MS	20



int arch_freq_get_on_cpu(int cpu)