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Commit 0e27c567 authored by Dietmar Eggemann's avatar Dietmar Eggemann Committed by Rafael J. Wysocki
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drivers base/arch_topology: provide frequency-invariant accounting support 



Implements the arch-specific (arm and arm64) frequency-invariance setter
function arch_set_freq_scale() which provides the following frequency
scaling factor:

  current_freq(cpu) << SCHED_CAPACITY_SHIFT / max_supported_freq(cpu)

One possible consumer of the frequency-invariance getter function
topology_get_freq_scale() is the Per-Entity Load Tracking (PELT)
mechanism of the task scheduler.

Allow inlining of topology_get_freq_scale() into the task scheduler
fast path (e.g. __update_load_avg_se()) by coding it as a static inline
function in the arch topology header file.

Signed-off-by: default avatarDietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 400ec74d

drivers/base/arch_topology.c

+14 −0
Original line number Diff line number Diff line
@@ -22,6 +22,20 @@ 
#include <linux/string.h>

#include <linux/sched/topology.h>



DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE;



void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,

			 unsigned long max_freq)

{

	unsigned long scale;

	int i;



	scale = (cur_freq << SCHED_CAPACITY_SHIFT) / max_freq;



	for_each_cpu(i, cpus)

		per_cpu(freq_scale, i) = scale;

}



static DEFINE_MUTEX(cpu_scale_mutex);

static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;

include/linux/arch_topology.h

+9 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
#define _LINUX_ARCH_TOPOLOGY_H_



#include <linux/types.h>

#include <linux/percpu.h>



void topology_normalize_cpu_scale(void);
@@ -16,4 +17,12 @@ unsigned long topology_get_cpu_scale(struct sched_domain *sd, int cpu); 


void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity);



DECLARE_PER_CPU(unsigned long, freq_scale);



static inline

unsigned long topology_get_freq_scale(struct sched_domain *sd, int cpu)

{

	return per_cpu(freq_scale, cpu);

}



#endif /* _LINUX_ARCH_TOPOLOGY_H_ */