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52 lines
1.5 KiB
C
52 lines
1.5 KiB
C
#include <linux/kernel.h>
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#include <linux/smp.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/cpufreq.h>
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#include <linux/slab.h>
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#include "mperf.h"
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static DEFINE_PER_CPU(struct aperfmperf, acfreq_old_perf);
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/* Called via smp_call_function_single(), on the target CPU */
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static void read_measured_perf_ctrs(void *_cur)
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{
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struct aperfmperf *am = _cur;
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get_aperfmperf(am);
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}
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/*
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* Return the measured active (C0) frequency on this CPU since last call
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* to this function.
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* Input: cpu number
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* Return: Average CPU frequency in terms of max frequency (zero on error)
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*
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* We use IA32_MPERF and IA32_APERF MSRs to get the measured performance
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* over a period of time, while CPU is in C0 state.
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* IA32_MPERF counts at the rate of max advertised frequency
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* IA32_APERF counts at the rate of actual CPU frequency
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* Only IA32_APERF/IA32_MPERF ratio is architecturally defined and
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* no meaning should be associated with absolute values of these MSRs.
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*/
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unsigned int cpufreq_get_measured_perf(struct cpufreq_policy *policy,
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unsigned int cpu)
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{
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struct aperfmperf perf;
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unsigned long ratio;
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unsigned int retval;
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if (smp_call_function_single(cpu, read_measured_perf_ctrs, &perf, 1))
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return 0;
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ratio = calc_aperfmperf_ratio(&per_cpu(acfreq_old_perf, cpu), &perf);
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per_cpu(acfreq_old_perf, cpu) = perf;
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retval = (policy->cpuinfo.max_freq * ratio) >> APERFMPERF_SHIFT;
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return retval;
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}
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EXPORT_SYMBOL_GPL(cpufreq_get_measured_perf);
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MODULE_LICENSE("GPL");
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