x86: sched: Provide arch implementations using aperf/mperf

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>
This commit is contained in:
Peter Zijlstra 2009-09-02 13:49:18 +02:00 коммит произвёл Ingo Molnar
Родитель 5cbc19a983
Коммит 47fe38fcff
3 изменённых файлов: 60 добавлений и 1 удалений

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@ -13,7 +13,7 @@ CFLAGS_common.o := $(nostackp)
obj-y := intel_cacheinfo.o addon_cpuid_features.o
obj-y += proc.o capflags.o powerflags.o common.o
obj-y += vmware.o hypervisor.o
obj-y += vmware.o hypervisor.o sched.o
obj-$(CONFIG_X86_32) += bugs.o cmpxchg.o
obj-$(CONFIG_X86_64) += bugs_64.o

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@ -0,0 +1,55 @@
#include <linux/sched.h>
#include <linux/math64.h>
#include <linux/percpu.h>
#include <linux/irqflags.h>
#include <asm/cpufeature.h>
#include <asm/processor.h>
#ifdef CONFIG_SMP
static DEFINE_PER_CPU(struct aperfmperf, old_perf);
static unsigned long scale_aperfmperf(void)
{
struct aperfmperf val, *old = &__get_cpu_var(old_perf);
unsigned long ratio, flags;
local_irq_save(flags);
get_aperfmperf(&val);
local_irq_restore(flags);
ratio = calc_aperfmperf_ratio(old, &val);
*old = val;
return ratio;
}
unsigned long arch_scale_freq_power(struct sched_domain *sd, int cpu)
{
/*
* do aperf/mperf on the cpu level because it includes things
* like turbo mode, which are relevant to full cores.
*/
if (boot_cpu_has(X86_FEATURE_APERFMPERF))
return scale_aperfmperf();
/*
* maybe have something cpufreq here
*/
return default_scale_freq_power(sd, cpu);
}
unsigned long arch_scale_smt_power(struct sched_domain *sd, int cpu)
{
/*
* aperf/mperf already includes the smt gain
*/
if (boot_cpu_has(X86_FEATURE_APERFMPERF))
return SCHED_LOAD_SCALE;
return default_scale_smt_power(sd, cpu);
}
#endif

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@ -992,6 +992,9 @@ static inline int test_sd_parent(struct sched_domain *sd, int flag)
return 0;
}
unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu);
unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu);
#else /* CONFIG_SMP */
struct sched_domain_attr;
@ -1003,6 +1006,7 @@ partition_sched_domains(int ndoms_new, struct cpumask *doms_new,
}
#endif /* !CONFIG_SMP */
struct io_context; /* See blkdev.h */