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Date: Tue, 2 Dec 2014 14:06:26 +0000 From: Morten Rasmussen <morten.rasmussen@....com> To: peterz@...radead.org, mingo@...hat.com Cc: dietmar.eggemann@....com, vincent.guittot@...aro.org, pjt@...gle.com, bsegall@...gle.com, mturquette@...aro.org, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, Morten Rasmussen <Morten.Rasmussen@....com>, Russell King <linux@....linux.org.uk>, Morten Rasmussen <morten.rasmussen@....com> Subject: [RFC PATCH 04/10] arm: Frequency invariant scheduler load-tracking support From: Morten Rasmussen <Morten.Rasmussen@....com> 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 <linux@....linux.org.uk> Signed-off-by: Morten Rasmussen <morten.rasmussen@....com> --- 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 89cfdd6..73ef337 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 (!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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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