128 lines
2.7 KiB
C
128 lines
2.7 KiB
C
|
/*
|
||
|
|
* x86 APERF/MPERF KHz calculation for
|
||
|
|
* /sys/.../cpufreq/scaling_cur_freq
|
||
|
|
*
|
||
|
|
* Copyright (C) 2017 Intel Corp.
|
||
|
|
* Author: Len Brown <len.brown@intel.com>
|
||
|
|
*
|
||
|
|
* This file is licensed under GPLv2.
|
||
|
|
*/
|
||
|
|
|
||
|
|
#include <linux/delay.h>
|
||
|
|
#include <linux/ktime.h>
|
||
|
|
#include <linux/math64.h>
|
||
|
|
#include <linux/percpu.h>
|
||
|
|
#include <linux/smp.h>
|
||
|
|
|
||
|
|
#include "cpu.h"
|
||
|
|
|
||
|
|
struct aperfmperf_sample {
|
||
|
|
unsigned int khz;
|
||
|
|
ktime_t time;
|
||
|
|
u64 aperf;
|
||
|
|
u64 mperf;
|
||
|
|
};
|
||
|
|
|
||
|
|
static DEFINE_PER_CPU(struct aperfmperf_sample, samples);
|
||
|
|
|
||
|
|
#define APERFMPERF_CACHE_THRESHOLD_MS 10
|
||
|
|
#define APERFMPERF_REFRESH_DELAY_MS 10
|
||
|
|
#define APERFMPERF_STALE_THRESHOLD_MS 1000
|
||
|
|
|
||
|
|
/*
|
||
|
|
* aperfmperf_snapshot_khz()
|
||
|
|
* On the current CPU, snapshot APERF, MPERF, and jiffies
|
||
|
|
* unless we already did it within 10ms
|
||
|
|
* calculate kHz, save snapshot
|
||
|
|
*/
|
||
|
|
static void aperfmperf_snapshot_khz(void *dummy)
|
||
|
|
{
|
||
|
|
u64 aperf, aperf_delta;
|
||
|
|
u64 mperf, mperf_delta;
|
||
|
|
struct aperfmperf_sample *s = this_cpu_ptr(&samples);
|
||
|
|
unsigned long flags;
|
||
|
|
|
||
|
|
local_irq_save(flags);
|
||
|
|
rdmsrl(MSR_IA32_APERF, aperf);
|
||
|
|
rdmsrl(MSR_IA32_MPERF, mperf);
|
||
|
|
local_irq_restore(flags);
|
||
|
|
|
||
|
|
aperf_delta = aperf - s->aperf;
|
||
|
|
mperf_delta = mperf - s->mperf;
|
||
|
|
|
||
|
|
/*
|
||
|
|
* There is no architectural guarantee that MPERF
|
||
|
|
* increments faster than we can read it.
|
||
|
|
*/
|
||
|
|
if (mperf_delta == 0)
|
||
|
|
return;
|
||
|
|
|
||
|
|
s->time = ktime_get();
|
||
|
|
s->aperf = aperf;
|
||
|
|
s->mperf = mperf;
|
||
|
|
s->khz = div64_u64((cpu_khz * aperf_delta), mperf_delta);
|
||
|
|
}
|
||
|
|
|
||
|
|
static bool aperfmperf_snapshot_cpu(int cpu, ktime_t now, bool wait)
|
||
|
|
{
|
||
|
|
s64 time_delta = ktime_ms_delta(now, per_cpu(samples.time, cpu));
|
||
|
|
|
||
|
|
/* Don't bother re-computing within the cache threshold time. */
|
||
|
|
if (time_delta < APERFMPERF_CACHE_THRESHOLD_MS)
|
||
|
|
return true;
|
||
|
|
|
||
|
|
smp_call_function_single(cpu, aperfmperf_snapshot_khz, NULL, wait);
|
||
|
|
|
||
|
|
/* Return false if the previous iteration was too long ago. */
|
||
|
|
return time_delta <= APERFMPERF_STALE_THRESHOLD_MS;
|
||
|
|
}
|
||
|
|
|
||
|
|
unsigned int aperfmperf_get_khz(int cpu)
|
||
|
|
{
|
||
|
|
if (!cpu_khz)
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
if (!static_cpu_has(X86_FEATURE_APERFMPERF))
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
aperfmperf_snapshot_cpu(cpu, ktime_get(), true);
|
||
|
|
return per_cpu(samples.khz, cpu);
|
||
|
|
}
|
||
|
|
|
||
|
|
void arch_freq_prepare_all(void)
|
||
|
|
{
|
||
|
|
ktime_t now = ktime_get();
|
||
|
|
bool wait = false;
|
||
|
|
int cpu;
|
||
|
|
|
||
|
|
if (!cpu_khz)
|
||
|
|
return;
|
||
|
|
|
||
|
|
if (!static_cpu_has(X86_FEATURE_APERFMPERF))
|
||
|
|
return;
|
||
|
|
|
||
|
|
for_each_online_cpu(cpu)
|
||
|
|
if (!aperfmperf_snapshot_cpu(cpu, now, false))
|
||
|
|
wait = true;
|
||
|
|
|
||
|
|
if (wait)
|
||
|
|
msleep(APERFMPERF_REFRESH_DELAY_MS);
|
||
|
|
}
|
||
|
|
|
||
|
|
unsigned int arch_freq_get_on_cpu(int cpu)
|
||
|
|
{
|
||
|
|
if (!cpu_khz)
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
if (!static_cpu_has(X86_FEATURE_APERFMPERF))
|
||
|
|
return 0;
|
||
|
|
|
||
|
|
if (aperfmperf_snapshot_cpu(cpu, ktime_get(), true))
|
||
|
|
return per_cpu(samples.khz, cpu);
|
||
|
|
|
||
|
|
msleep(APERFMPERF_REFRESH_DELAY_MS);
|
||
|
|
smp_call_function_single(cpu, aperfmperf_snapshot_khz, NULL, 1);
|
||
|
|
|
||
|
|
return per_cpu(samples.khz, cpu);
|
||
|
|
}
|