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