From: Morten Rasmussen <[email protected]>
Implements arch-specific function to provide the scheduler with a
frequency scaling correction factor for more accurate load-tracking. The
factor is:
current_freq(cpu) * SCHED_CAPACITY_SCALE / max_freq(cpu)
This implementation only provides frequency invariance. No
micro-architecture invariance yet.
Cc: Russell King <[email protected]>
Signed-off-by: Morten Rasmussen <[email protected]>
---
arch/arm/kernel/topology.c | 33 +++++++++++++++++++++++++++++++++
1 file changed, 33 insertions(+)
diff --git a/arch/arm/kernel/topology.c b/arch/arm/kernel/topology.c
index 08b7847..a1274e6 100644
--- a/arch/arm/kernel/topology.c
+++ b/arch/arm/kernel/topology.c
@@ -169,6 +169,39 @@ static void update_cpu_capacity(unsigned int cpu)
cpu, arch_scale_cpu_capacity(NULL, cpu));
}
+/*
+ * Scheduler load-tracking scale-invariance
+ *
+ * Provides the scheduler with a scale-invariance correction factor that
+ * compensates for frequency scaling.
+ */
+
+static DEFINE_PER_CPU(atomic_long_t, cpu_curr_freq);
+static DEFINE_PER_CPU(atomic_long_t, cpu_max_freq);
+
+/* cpufreq callback function setting current cpu frequency */
+void arch_scale_set_curr_freq(int cpu, unsigned long freq)
+{
+ atomic_long_set(&per_cpu(cpu_curr_freq, cpu), freq);
+}
+
+/* cpufreq callback function setting max cpu frequency */
+void arch_scale_set_max_freq(int cpu, unsigned long freq)
+{
+ atomic_long_set(&per_cpu(cpu_max_freq, cpu), freq);
+}
+
+unsigned long arch_scale_freq_capacity(struct sched_domain *sd, int cpu)
+{
+ unsigned long curr = atomic_long_read(&per_cpu(cpu_curr_freq, cpu));
+ unsigned long max = atomic_long_read(&per_cpu(cpu_max_freq, cpu));
+
+ if (!curr || !max)
+ return SCHED_CAPACITY_SCALE;
+
+ return (curr * SCHED_CAPACITY_SCALE) / max;
+}
+
#else
static inline void parse_dt_topology(void) {}
static inline void update_cpu_capacity(unsigned int cpuid) {}
--
1.9.1
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