9c5320c8ea
Future AMD processors, starting with Family 16h, can provide software with feedback on how the workload may respond to frequency change -- memory-bound workloads will not benefit from higher frequency, where as compute-bound workloads will. This patch enables this "frequency sensitivity feedback" to aid the ondemand governor to make better frequency change decisions by hooking into the powersave bias. Signed-off-by: Jacob Shin <jacob.shin@amd.com> Acked-by: Thomas Renninger <trenn@suse.de> Acked-by: Borislav Petkov <bp@suse.de> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
148 lines
3.8 KiB
C
148 lines
3.8 KiB
C
/*
|
|
* amd_freq_sensitivity.c: AMD frequency sensitivity feedback powersave bias
|
|
* for the ondemand governor.
|
|
*
|
|
* Copyright (C) 2013 Advanced Micro Devices, Inc.
|
|
*
|
|
* Author: Jacob Shin <jacob.shin@amd.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/module.h>
|
|
#include <linux/types.h>
|
|
#include <linux/percpu-defs.h>
|
|
#include <linux/init.h>
|
|
#include <linux/mod_devicetable.h>
|
|
|
|
#include <asm/msr.h>
|
|
#include <asm/cpufeature.h>
|
|
|
|
#include "cpufreq_governor.h"
|
|
|
|
#define MSR_AMD64_FREQ_SENSITIVITY_ACTUAL 0xc0010080
|
|
#define MSR_AMD64_FREQ_SENSITIVITY_REFERENCE 0xc0010081
|
|
#define CLASS_CODE_SHIFT 56
|
|
#define POWERSAVE_BIAS_MAX 1000
|
|
#define POWERSAVE_BIAS_DEF 400
|
|
|
|
struct cpu_data_t {
|
|
u64 actual;
|
|
u64 reference;
|
|
unsigned int freq_prev;
|
|
};
|
|
|
|
static DEFINE_PER_CPU(struct cpu_data_t, cpu_data);
|
|
|
|
static unsigned int amd_powersave_bias_target(struct cpufreq_policy *policy,
|
|
unsigned int freq_next,
|
|
unsigned int relation)
|
|
{
|
|
int sensitivity;
|
|
long d_actual, d_reference;
|
|
struct msr actual, reference;
|
|
struct cpu_data_t *data = &per_cpu(cpu_data, policy->cpu);
|
|
struct dbs_data *od_data = policy->governor_data;
|
|
struct od_dbs_tuners *od_tuners = od_data->tuners;
|
|
struct od_cpu_dbs_info_s *od_info =
|
|
od_data->cdata->get_cpu_dbs_info_s(policy->cpu);
|
|
|
|
if (!od_info->freq_table)
|
|
return freq_next;
|
|
|
|
rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_ACTUAL,
|
|
&actual.l, &actual.h);
|
|
rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_REFERENCE,
|
|
&reference.l, &reference.h);
|
|
actual.h &= 0x00ffffff;
|
|
reference.h &= 0x00ffffff;
|
|
|
|
/* counter wrapped around, so stay on current frequency */
|
|
if (actual.q < data->actual || reference.q < data->reference) {
|
|
freq_next = policy->cur;
|
|
goto out;
|
|
}
|
|
|
|
d_actual = actual.q - data->actual;
|
|
d_reference = reference.q - data->reference;
|
|
|
|
/* divide by 0, so stay on current frequency as well */
|
|
if (d_reference == 0) {
|
|
freq_next = policy->cur;
|
|
goto out;
|
|
}
|
|
|
|
sensitivity = POWERSAVE_BIAS_MAX -
|
|
(POWERSAVE_BIAS_MAX * (d_reference - d_actual) / d_reference);
|
|
|
|
clamp(sensitivity, 0, POWERSAVE_BIAS_MAX);
|
|
|
|
/* this workload is not CPU bound, so choose a lower freq */
|
|
if (sensitivity < od_tuners->powersave_bias) {
|
|
if (data->freq_prev == policy->cur)
|
|
freq_next = policy->cur;
|
|
|
|
if (freq_next > policy->cur)
|
|
freq_next = policy->cur;
|
|
else if (freq_next < policy->cur)
|
|
freq_next = policy->min;
|
|
else {
|
|
unsigned int index;
|
|
|
|
cpufreq_frequency_table_target(policy,
|
|
od_info->freq_table, policy->cur - 1,
|
|
CPUFREQ_RELATION_H, &index);
|
|
freq_next = od_info->freq_table[index].frequency;
|
|
}
|
|
|
|
data->freq_prev = freq_next;
|
|
} else
|
|
data->freq_prev = 0;
|
|
|
|
out:
|
|
data->actual = actual.q;
|
|
data->reference = reference.q;
|
|
return freq_next;
|
|
}
|
|
|
|
static int __init amd_freq_sensitivity_init(void)
|
|
{
|
|
u64 val;
|
|
|
|
if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
|
|
return -ENODEV;
|
|
|
|
if (!static_cpu_has(X86_FEATURE_PROC_FEEDBACK))
|
|
return -ENODEV;
|
|
|
|
if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val))
|
|
return -ENODEV;
|
|
|
|
if (!(val >> CLASS_CODE_SHIFT))
|
|
return -ENODEV;
|
|
|
|
od_register_powersave_bias_handler(amd_powersave_bias_target,
|
|
POWERSAVE_BIAS_DEF);
|
|
return 0;
|
|
}
|
|
late_initcall(amd_freq_sensitivity_init);
|
|
|
|
static void __exit amd_freq_sensitivity_exit(void)
|
|
{
|
|
od_unregister_powersave_bias_handler();
|
|
}
|
|
module_exit(amd_freq_sensitivity_exit);
|
|
|
|
static const struct x86_cpu_id amd_freq_sensitivity_ids[] = {
|
|
X86_FEATURE_MATCH(X86_FEATURE_PROC_FEEDBACK),
|
|
{}
|
|
};
|
|
MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids);
|
|
|
|
MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>");
|
|
MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for "
|
|
"the ondemand governor.");
|
|
MODULE_LICENSE("GPL");
|