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authorDietmar Eggemann <dietmar.eggemann@arm.com>2017-09-26 17:41:10 +0100
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2017-10-03 02:37:53 +0200
commit0e27c567d1673137b06aa96bb7aef635fb657dee (patch)
treebcbb7041ef1af0a73336595a4e9d72ec5fedb813
parent400ec74d3b3784a48b09db9518aa2c4b6d4e497f (diff)
downloadlinux-0e27c567d1673137b06aa96bb7aef635fb657dee.tar.gz
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>
-rw-r--r--drivers/base/arch_topology.c14
-rw-r--r--include/linux/arch_topology.h9
2 files changed, 23 insertions, 0 deletions
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index e9bb368..416ec2f 100644
--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -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;
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 @@ 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_ */