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/uapi/asm/msr-index.h | 1 + drivers/cpufreq/Kconfig.x86 | 10 +++ drivers/cpufreq/Makefile | 1 + drivers/cpufreq/amd_freq_sensitivity.c | 147 ++++++++++++++++++++++++++++++++ 4 files changed, 159 insertions(+) create mode 100644 drivers/cpufreq/amd_freq_sensitivity.c diff --git a/arch/x86/include/uapi/asm/msr-index.h b/arch/x86/include/uapi/asm/msr-index.h index 7a060f4..b2e6c49 100644 --- a/arch/x86/include/uapi/asm/msr-index.h +++ b/arch/x86/include/uapi/asm/msr-index.h @@ -173,6 +173,7 @@ #define MSR_AMD64_TSC_RATIO 0xc0000104 #define MSR_AMD64_NB_CFG 0xc001001f #define MSR_AMD64_PATCH_LOADER 0xc0010020 +#define MSR_AMD64_FREQ_SENSITIVITY 0xc0010080 #define MSR_AMD64_OSVW_ID_LENGTH 0xc0010140 #define MSR_AMD64_OSVW_STATUS 0xc0010141 #define MSR_AMD64_DC_CFG 0xc0011022 diff --git a/drivers/cpufreq/Kconfig.x86 b/drivers/cpufreq/Kconfig.x86 index d7dc0ed..6c714b0 100644 --- a/drivers/cpufreq/Kconfig.x86 +++ b/drivers/cpufreq/Kconfig.x86 @@ -129,6 +129,16 @@ 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 + help + This adds support for 'frequency sensitivity feedback' feature on + supported AMD processors, which hooks into the ondemand governor's + powersave bias to influence frequency change decisions. + + 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..997feb0 --- /dev/null +++ b/drivers/cpufreq/amd_freq_sensitivity.c @@ -0,0 +1,147 @@ +/* + * amd_freq_sensitivity.c: AMD "frequency sensitivity feedback" powersave bias + * for ondemand governor. + * + * Copyright (C) 2013 Advanced Micro Devices, Inc. + * + * 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/module.h> +#include <linux/types.h> +#include <linux/percpu-defs.h> +#include <linux/init.h> + +#include "cpufreq_governor.h" + +#define PROC_FEEDBACK_INTERFACE_SHIFT 11 +#define CLASS_CODE_SHIFT 56 +#define CLASS_CODE_MASK 0xff +#define CLASS_CODE_CORE_FREQUENCY_SENSITIVITY 0x01 + +static u32 msr_addr; + +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); + + rdmsr_on_cpu(policy->cpu, msr_addr, &actual.l, &actual.h); + rdmsr_on_cpu(policy->cpu, msr_addr + 1, &reference.l, &reference.h); + actual.h &= 0x00ffffff; + reference.h &= 0x00ffffff; + + if (!od_info->freq_table) + goto out; + + /* counter wrapped around, so push until next check */ + 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 push as well */ + if (d_reference == 0) { + freq_next = policy->cur; + goto out; + } + + sensitivity = 1000 - (1000 * (d_reference - d_actual) / d_reference); + + if (sensitivity > 1000) + sensitivity = 1000; + else if (sensitivity < 0) + sensitivity = 0; + + /* 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 = 0; + + 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 i; + u32 eax, edx, dummy; + + if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD) + return -ENODEV; + + cpuid(0x80000007, &eax, &dummy, &dummy, &edx); + + if (!(edx & (1 << PROC_FEEDBACK_INTERFACE_SHIFT))) + return -ENODEV; + + for (i = 0; i < (eax & 0xf); i++) { + u64 val; + u32 addr = MSR_AMD64_FREQ_SENSITIVITY + (i * 2); + + rdmsrl(addr, val); + + if (((val >> CLASS_CODE_SHIFT) & CLASS_CODE_MASK) + == CLASS_CODE_CORE_FREQUENCY_SENSITIVITY) { + msr_addr = addr; + break; + } + } + + if (!msr_addr) + return -ENODEV; + + od_register_powersave_bias_function(amd_powersave_bias_target); + return 0; +} +module_init(amd_freq_sensitivity_init); + +static void __exit amd_freq_sensitivity_exit(void) +{ + od_unregister_powersave_bias_function(); +} +module_exit(amd_freq_sensitivity_exit); + +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/
