From: Dietmar Eggemann <dietmar.eggemann@arm.com>
Date: Fri, 30 Jun 2017 16:00:23 +0000 (+0100)
Subject: ANDROID: drivers base/arch_topology: provide frequency-invariant accounting support
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=d283e80e93f47fd67c89599d2ebf6ba264c37586;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git

ANDROID: 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.

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>
---

diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c
index df2bab7de5db..06c8009cd000 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 d4fcb0efb896..f53438c77bf5 100644
--- a/include/linux/arch_topology.h
+++ b/include/linux/arch_topology.h
@@ -6,6 +6,7 @@
 #define _LINUX_ARCH_TOPOLOGY_H_
 
 #include <linux/types.h>
+#include <linux/percpu.h>
 
 void topology_normalize_cpu_scale(void);
 
@@ -17,4 +18,12 @@ 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_ */