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Commit 47fe38fc authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

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: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5cbc19a9

arch/x86/kernel/cpu/Makefile

+1 −1
Original line number Original line Diff line number Diff line
@@ -13,7 +13,7 @@ CFLAGS_common.o := $(nostackp) 




obj-y			:= intel_cacheinfo.o addon_cpuid_features.o

obj-y			:= intel_cacheinfo.o addon_cpuid_features.o

obj-y			+= proc.o capflags.o powerflags.o common.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_32)	+= bugs.o cmpxchg.o

obj-$(CONFIG_X86_64)	+= bugs_64.o

obj-$(CONFIG_X86_64)	+= bugs_64.o

arch/x86/kernel/cpu/sched.c

0 → 100644
+55 −0
Original line number Original line Diff line number Diff line 
#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

include/linux/sched.h

+4 −0
Original line number Original line Diff line number Diff line
@@ -992,6 +992,9 @@ static inline int test_sd_parent(struct sched_domain *sd, int flag) 
	return 0;

	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 */

#else /* CONFIG_SMP */





struct sched_domain_attr;

struct sched_domain_attr;
@@ -1003,6 +1006,7 @@ partition_sched_domains(int ndoms_new, struct cpumask *doms_new, 
}

}

#endif	/* !CONFIG_SMP */

#endif	/* !CONFIG_SMP */







struct io_context;			/* See blkdev.h */

struct io_context;			/* See blkdev.h */