Thread (17 messages) 17 messages, 4 authors, 2021-10-28

Re: [PATCH v2 1/5] arch_topology: Introduce thermal pressure update function

From: Bjorn Andersson <hidden>
Date: 2021-10-27 18:41:33
Also in: linux-arm-msm, linux-pm, lkml

On Fri 15 Oct 07:45 PDT 2021, Lukasz Luba wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/include/asm/topology.h b/arch/arm64/include/asm/topology.h
[..]
+/**
+ * topology_thermal_pressure_update() - Update thermal pressure for CPUs
+ * @cpus	: The related CPUs for which capacity has been reduced
+ * @capped_freq	: The maximum allowed frequency that CPUs can run at
I know this matches what I see in e.g. the Qualcomm cpufreq hw driver,
but in what cases will @capped_freq differ from
cpufreq_get_hw_max_freq(cpumask_first(cpus))?

Regards,
Bjorn
quoted hunk ↗ jump to hunk
+ *
+ * Update the value of thermal pressure for all @cpus in the mask. The
+ * cpumask should include all (online+offline) affected CPUs, to avoid
+ * operating on stale data when hot-plug is used for some CPUs. The
+ * @capped_freq must be less or equal to the max possible frequency and
+ * reflects the currently allowed max CPUs frequency due to thermal capping.
+ * The @capped_freq must be provided in kHz.
+ */
+void topology_thermal_pressure_update(const struct cpumask *cpus,
+				      unsigned long capped_freq)
+{
+	unsigned long max_capacity, capacity;
+	int cpu;
+
+	if (!cpus)
+		return;
+
+	cpu = cpumask_first(cpus);
+	max_capacity = arch_scale_cpu_capacity(cpu);
+
+	/* Convert to MHz scale which is used in 'freq_factor' */
+	capped_freq /= 1000;
+
+	capacity = mult_frac(capped_freq, max_capacity,
+			     per_cpu(freq_factor, cpu));
+
+	arch_set_thermal_pressure(cpus, max_capacity - capacity);
+}
+EXPORT_SYMBOL_GPL(topology_thermal_pressure_update);
+
 static ssize_t cpu_capacity_show(struct device *dev,
 				 struct device_attribute *attr,
 				 char *buf)
@@ -220,7 +255,6 @@ static void update_topology_flags_workfn(struct work_struct *work)
 	update_topology = 0;
 }
 
-static DEFINE_PER_CPU(u32, freq_factor) = 1;
 static u32 *raw_capacity;
 
 static int free_raw_capacity(void)
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