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47fe38fcff
APERF/MPERF support for cpu_power. APERF/MPERF is arch defined to be a relative scale of work capacity per logical cpu, this is assumed to include SMT and Turbo mode. APERF/MPERF are specified to both reset to 0 when either counter wraps, which is highly inconvenient, since that'll give a blimp when that happens. The manual specifies writing 0 to the counters after each read, but that's 1) too expensive, and 2) destroys the possibility of sharing these counters with other users, so we live with the blimp - the other existing user does too. Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
55 lines
1.1 KiB
C
55 lines
1.1 KiB
C
#include <linux/sched.h>
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#include <linux/math64.h>
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#include <linux/percpu.h>
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#include <linux/irqflags.h>
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#include <asm/cpufeature.h>
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#include <asm/processor.h>
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#ifdef CONFIG_SMP
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static DEFINE_PER_CPU(struct aperfmperf, old_perf);
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static unsigned long scale_aperfmperf(void)
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{
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struct aperfmperf val, *old = &__get_cpu_var(old_perf);
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unsigned long ratio, flags;
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local_irq_save(flags);
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get_aperfmperf(&val);
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local_irq_restore(flags);
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ratio = calc_aperfmperf_ratio(old, &val);
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*old = val;
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return ratio;
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}
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unsigned long arch_scale_freq_power(struct sched_domain *sd, int cpu)
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{
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/*
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* do aperf/mperf on the cpu level because it includes things
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* like turbo mode, which are relevant to full cores.
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*/
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if (boot_cpu_has(X86_FEATURE_APERFMPERF))
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return scale_aperfmperf();
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/*
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* maybe have something cpufreq here
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*/
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return default_scale_freq_power(sd, cpu);
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}
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unsigned long arch_scale_smt_power(struct sched_domain *sd, int cpu)
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{
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/*
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* aperf/mperf already includes the smt gain
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*/
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if (boot_cpu_has(X86_FEATURE_APERFMPERF))
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return SCHED_LOAD_SCALE;
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return default_scale_smt_power(sd, cpu);
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}
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#endif
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