From 2c58b6ac7774436ccbd350109155ffa011253867 Mon Sep 17 00:00:00 2001 From: Morten Rasmussen Date: Mon, 22 Sep 2014 17:24:03 +0100 Subject: arm: Frequency invariant scheduler load-tracking support 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 Signed-off-by: Morten Rasmussen --- 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 2310bfbc1782..dcfc4842fda6 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) {} -- cgit v1.2.3