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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
/*
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* amd_freq_sensitivity.c: AMD frequency sensitivity feedback powersave bias
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* for the ondemand governor.
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*
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* Copyright (C) 2013 Advanced Micro Devices, Inc.
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*
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* Author: Jacob Shin <jacob.shin@amd.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/percpu-defs.h>
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#include <linux/init.h>
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#include <linux/mod_devicetable.h>
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#include <asm/msr.h>
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#include <asm/cpufeature.h>
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#include "cpufreq_governor.h"
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#define MSR_AMD64_FREQ_SENSITIVITY_ACTUAL 0xc0010080
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#define MSR_AMD64_FREQ_SENSITIVITY_REFERENCE 0xc0010081
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#define CLASS_CODE_SHIFT 56
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#define POWERSAVE_BIAS_MAX 1000
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#define POWERSAVE_BIAS_DEF 400
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struct cpu_data_t {
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u64 actual;
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u64 reference;
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unsigned int freq_prev;
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};
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static DEFINE_PER_CPU(struct cpu_data_t, cpu_data);
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static unsigned int amd_powersave_bias_target(struct cpufreq_policy *policy,
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unsigned int freq_next,
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unsigned int relation)
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{
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int sensitivity;
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long d_actual, d_reference;
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struct msr actual, reference;
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struct cpu_data_t *data = &per_cpu(cpu_data, policy->cpu);
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struct dbs_data *od_data = policy->governor_data;
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struct od_dbs_tuners *od_tuners = od_data->tuners;
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struct od_cpu_dbs_info_s *od_info =
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od_data->cdata->get_cpu_dbs_info_s(policy->cpu);
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if (!od_info->freq_table)
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return freq_next;
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rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_ACTUAL,
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&actual.l, &actual.h);
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rdmsr_on_cpu(policy->cpu, MSR_AMD64_FREQ_SENSITIVITY_REFERENCE,
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&reference.l, &reference.h);
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actual.h &= 0x00ffffff;
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reference.h &= 0x00ffffff;
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/* counter wrapped around, so stay on current frequency */
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if (actual.q < data->actual || reference.q < data->reference) {
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freq_next = policy->cur;
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goto out;
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}
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d_actual = actual.q - data->actual;
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d_reference = reference.q - data->reference;
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/* divide by 0, so stay on current frequency as well */
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if (d_reference == 0) {
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freq_next = policy->cur;
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goto out;
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}
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sensitivity = POWERSAVE_BIAS_MAX -
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(POWERSAVE_BIAS_MAX * (d_reference - d_actual) / d_reference);
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clamp(sensitivity, 0, POWERSAVE_BIAS_MAX);
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/* this workload is not CPU bound, so choose a lower freq */
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if (sensitivity < od_tuners->powersave_bias) {
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if (data->freq_prev == policy->cur)
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freq_next = policy->cur;
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if (freq_next > policy->cur)
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freq_next = policy->cur;
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else if (freq_next < policy->cur)
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freq_next = policy->min;
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else {
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unsigned int index;
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cpufreq_frequency_table_target(policy,
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od_info->freq_table, policy->cur - 1,
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CPUFREQ_RELATION_H, &index);
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freq_next = od_info->freq_table[index].frequency;
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}
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data->freq_prev = freq_next;
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} else
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data->freq_prev = 0;
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out:
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data->actual = actual.q;
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data->reference = reference.q;
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return freq_next;
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}
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static int __init amd_freq_sensitivity_init(void)
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{
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u64 val;
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if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD)
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return -ENODEV;
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if (!static_cpu_has(X86_FEATURE_PROC_FEEDBACK))
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return -ENODEV;
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if (rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val))
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return -ENODEV;
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if (!(val >> CLASS_CODE_SHIFT))
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return -ENODEV;
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od_register_powersave_bias_handler(amd_powersave_bias_target,
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POWERSAVE_BIAS_DEF);
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return 0;
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}
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late_initcall(amd_freq_sensitivity_init);
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static void __exit amd_freq_sensitivity_exit(void)
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{
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od_unregister_powersave_bias_handler();
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}
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module_exit(amd_freq_sensitivity_exit);
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static const struct x86_cpu_id amd_freq_sensitivity_ids[] = {
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X86_FEATURE_MATCH(X86_FEATURE_PROC_FEEDBACK),
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{}
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};
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MODULE_DEVICE_TABLE(x86cpu, amd_freq_sensitivity_ids);
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MODULE_AUTHOR("Jacob Shin <jacob.shin@amd.com>");
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MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for "
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"the ondemand governor.");
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MODULE_LICENSE("GPL");
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