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x86: sched: Provide arch implementations using aperf/mperf

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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
committed by Ingo Molnar
parent 5cbc19a983
commit 47fe38fcff
3 changed files with 60 additions and 1 deletions
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4
include/linux/sched.h
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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 */