[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20240603082154.3830591-5-beata.michalska@arm.com>
Date: Mon, 3 Jun 2024 09:21:54 +0100
From: Beata Michalska <beata.michalska@....com>
To: linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.org,
ionela.voinescu@....com,
sudeep.holla@....com,
will@...nel.org,
catalin.marinas@....com,
vincent.guittot@...aro.org,
vanshikonda@...amperecomputing.com
Cc: sumitg@...dia.com,
yang@...amperecomputing.com,
lihuisong@...wei.com,
viresh.kumar@...aro.org,
rafael@...nel.org
Subject: [PATCH v6 4/4] 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: Vanshidhar Konda <vanshikonda@...amperecomputing.com>
Signed-off-by: Beata Michalska <beata.michalska@....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 2c002d2c3e0b..56c5b2e632b4 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
Powered by blists - more mailing lists