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 <[email protected]> --- arch/x86/include/asm/cpufeature.h | 1 + arch/x86/kernel/cpu/scattered.c | 3 +- drivers/cpufreq/Kconfig.x86 | 17 ++++ drivers/cpufreq/Makefile | 1 + drivers/cpufreq/amd_freq_sensitivity.c | 150 ++++++++++++++++++++++++++++++++ 5 files changed, 171 insertions(+), 1 deletion(-) create mode 100644 drivers/cpufreq/amd_freq_sensitivity.c diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 93fe929..9e22520 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -182,6 +182,7 @@ #define X86_FEATURE_PTS (7*32+ 6) /* Intel Package Thermal Status */ #define X86_FEATURE_DTHERM (7*32+ 7) /* Digital Thermal Sensor */ #define X86_FEATURE_HW_PSTATE (7*32+ 8) /* AMD HW-PState */ +#define X86_FEATURE_PROC_FEEDBACK (7*32+ 9) /* AMD ProcFeedbackInterface */ /* Virtualization flags: Linux defined, word 8 */ #define X86_FEATURE_TPR_SHADOW (8*32+ 0) /* Intel TPR Shadow */ diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c index ee8e9ab..d92b5da 100644 --- a/arch/x86/kernel/cpu/scattered.c +++ b/arch/x86/kernel/cpu/scattered.c @@ -39,8 +39,9 @@ void __cpuinit init_scattered_cpuid_features(struct cpuinfo_x86 *c) { X86_FEATURE_APERFMPERF, CR_ECX, 0, 0x00000006, 0 }, { X86_FEATURE_EPB, CR_ECX, 3, 0x00000006, 0 }, { X86_FEATURE_XSAVEOPT, CR_EAX, 0, 0x0000000d, 1 }, - { X86_FEATURE_CPB, CR_EDX, 9, 0x80000007, 0 }, { X86_FEATURE_HW_PSTATE, CR_EDX, 7, 0x80000007, 0 }, + { X86_FEATURE_CPB, CR_EDX, 9, 0x80000007, 0 }, + { X86_FEATURE_PROC_FEEDBACK, CR_EDX,11, 0x80000007, 0 }, { X86_FEATURE_NPT, CR_EDX, 0, 0x8000000a, 0 }, { X86_FEATURE_LBRV, CR_EDX, 1, 0x8000000a, 0 }, { X86_FEATURE_SVML, CR_EDX, 2, 0x8000000a, 0 }, diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86 index d7dc0ed..018fced 100644 --- a/drivers/cpufreq/Kconfig.x86 +++ b/drivers/cpufreq/Kconfig.x86 @@ -129,6 +129,23 @@ config X86_POWERNOW_K8 For details, take a look at <file:Documentation/cpu-freq/>. +config X86_AMD_FREQ_SENSITIVITY + tristate "AMD frequency sensitivity feedback powersave bias" + depends on CPU_FREQ_GOV_ONDEMAND && X86_ACPI_CPUFREQ && CPU_SUP_AMD + help + This adds AMD specific powersave bias function to the ondemand + governor; which can be used to help ondemand governor make more power + conscious frequency change decisions based on feedback from hardware + (availble on AMD Family 16h and above). + + Hardware feedback tells software how "sensitive" to frequency changes + the CPUs' workloads are. CPU-bound workloads will be more sensitive + -- they will perform better as frequency increases. Memory/IO-bound + workloads will be less sensitive -- they will not necessarily perform + better as frequnecy increases. + + If in doubt, say N. + config X86_GX_SUSPMOD tristate "Cyrix MediaGX/NatSemi Geode Suspend Modulation" depends on X86_32 && PCI diff --git a/drivers/cpufreq/Makefile b/drivers/cpufreq/Makefile index 863fd18..01dfdaf 100644 --- a/drivers/cpufreq/Makefile +++ b/drivers/cpufreq/Makefile @@ -41,6 +41,7 @@ obj-$(CONFIG_X86_SPEEDSTEP_CENTRINO) += speedstep-centrino.o obj-$(CONFIG_X86_P4_CLOCKMOD) += p4-clockmod.o obj-$(CONFIG_X86_CPUFREQ_NFORCE2) += cpufreq-nforce2.o obj-$(CONFIG_X86_INTEL_PSTATE) += intel_pstate.o +obj-$(CONFIG_X86_AMD_FREQ_SENSITIVITY) += amd_freq_sensitivity.o ################################################################################## # ARM SoC drivers diff --git a/drivers/cpufreq/amd_freq_sensitivity.c b/drivers/cpufreq/amd_freq_sensitivity.c new file mode 100644 index 0000000..e3e62d2 --- /dev/null +++ b/drivers/cpufreq/amd_freq_sensitivity.c @@ -0,0 +1,150 @@ +/* + * amd_freq_sensitivity.c: AMD frequency sensitivity feedback powersave bias + * for the ondemand governor. + * + * Copyright (C) 2013 Advanced Micro Devices, Inc. + * + * Author: Jacob Shin <[email protected]> + * + * 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 CLASS_CODE_CORE_FREQ_SENSITIVITY 0x01 +#define POWERSAVE_BIAS_MAX 1000 + +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) +{ + int err; + u64 val; + + if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) + return -ENODEV; + + if (!static_cpu_has(X86_FEATURE_PROC_FEEDBACK)) + return -ENODEV; + + err = rdmsrl_safe(MSR_AMD64_FREQ_SENSITIVITY_ACTUAL, &val); + + if (err) + return -ENODEV; + + if ((val >> CLASS_CODE_SHIFT) != CLASS_CODE_CORE_FREQ_SENSITIVITY) + return -ENODEV; + + od_register_powersave_bias_handler(amd_powersave_bias_target); + return 0; +} +module_init(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 <[email protected]>"); +MODULE_DESCRIPTION("AMD frequency sensitivity feedback powersave bias for " + "the ondemand governor."); +MODULE_LICENSE("GPL"); -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
