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.
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Change-Id: I7a0fadc160d85daf9e35e346391c5d0bb9167d71
Signed-off-by: Chris Redpath <chris.redpath@arm.com>
#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;
#define _LINUX_ARCH_TOPOLOGY_H_
#include <linux/types.h>
+#include <linux/percpu.h>
void topology_normalize_cpu_scale(void);
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_ */