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: Dietmar Eggemann <dietmar.eggemann@arm.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/include/linux/arch_topology.h b/include/linux/arch_topology.h
index 716ce58..f6e4903 100644
--- a/include/linux/arch_topology.h
+++ b/include/linux/arch_topology.h
@@ -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 @@
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_ */