# SPDX-License-Identifier: GPL-2.0-only menu "CPU Frequency scaling" config CPU_FREQ bool "CPU Frequency scaling" help CPU Frequency scaling allows you to change the clock speed of CPUs on the fly. This is a nice method to save power, because the lower the CPU clock speed, the less power the CPU consumes. Note that this driver doesn't automatically change the CPU clock speed, you need to either enable a dynamic cpufreq governor (see below) after boot, or use a userspace tool. For details, take a look at . If in doubt, say N. if CPU_FREQ config CPU_FREQ_GOV_ATTR_SET bool config CPU_FREQ_GOV_COMMON select CPU_FREQ_GOV_ATTR_SET select IRQ_WORK bool config CPU_FREQ_STAT bool "CPU frequency transition statistics" help Export CPU frequency statistics information through sysfs. If in doubt, say N. choice prompt "Default CPUFreq governor" default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1110_CPUFREQ default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if ARM64 || ARM default CPU_FREQ_DEFAULT_GOV_SCHEDUTIL if (X86_INTEL_PSTATE || X86_AMD_PSTATE) && SMP default CPU_FREQ_DEFAULT_GOV_PERFORMANCE help This option sets which CPUFreq governor shall be loaded at startup. If in doubt, use the default setting. config CPU_FREQ_DEFAULT_GOV_PERFORMANCE bool "performance" select CPU_FREQ_GOV_PERFORMANCE help Use the CPUFreq governor 'performance' as default. This sets the frequency statically to the highest frequency supported by the CPU. config CPU_FREQ_DEFAULT_GOV_POWERSAVE bool "powersave" select CPU_FREQ_GOV_POWERSAVE help Use the CPUFreq governor 'powersave' as default. This sets the frequency statically to the lowest frequency supported by the CPU. config CPU_FREQ_DEFAULT_GOV_USERSPACE bool "userspace" select CPU_FREQ_GOV_USERSPACE help Use the CPUFreq governor 'userspace' as default. This allows you to set the CPU frequency manually or when a userspace program shall be able to set the CPU dynamically without having to enable the userspace governor manually. config CPU_FREQ_DEFAULT_GOV_ONDEMAND bool "ondemand" depends on !(X86_INTEL_PSTATE && SMP) select CPU_FREQ_GOV_ONDEMAND select CPU_FREQ_GOV_PERFORMANCE help Use the CPUFreq governor 'ondemand' as default. This allows you to get a full dynamic frequency capable system by simply loading your cpufreq low-level hardware driver. Be aware that not all cpufreq drivers support the ondemand governor. If unsure have a look at the help section of the driver. Fallback governor will be the performance governor. config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE bool "conservative" depends on !(X86_INTEL_PSTATE && SMP) select CPU_FREQ_GOV_CONSERVATIVE select CPU_FREQ_GOV_PERFORMANCE help Use the CPUFreq governor 'conservative' as default. This allows you to get a full dynamic frequency capable system by simply loading your cpufreq low-level hardware driver. Be aware that not all cpufreq drivers support the conservative governor. If unsure have a look at the help section of the driver. Fallback governor will be the performance governor. config CPU_FREQ_DEFAULT_GOV_SCHEDUTIL bool "schedutil" depends on SMP select CPU_FREQ_GOV_SCHEDUTIL select CPU_FREQ_GOV_PERFORMANCE help Use the 'schedutil' CPUFreq governor by default. If unsure, have a look at the help section of that governor. The fallback governor will be 'performance'. endchoice config CPU_FREQ_GOV_PERFORMANCE tristate "'performance' governor" help This cpufreq governor sets the frequency statically to the highest available CPU frequency. To compile this driver as a module, choose M here: the module will be called cpufreq_performance. If in doubt, say Y. config CPU_FREQ_GOV_POWERSAVE tristate "'powersave' governor" help This cpufreq governor sets the frequency statically to the lowest available CPU frequency. To compile this driver as a module, choose M here: the module will be called cpufreq_powersave. If in doubt, say Y. config CPU_FREQ_GOV_USERSPACE tristate "'userspace' governor for userspace frequency scaling" help Enable this cpufreq governor when you either want to set the CPU frequency manually or when a userspace program shall be able to set the CPU dynamically, like on LART . To compile this driver as a module, choose M here: the module will be called cpufreq_userspace. If in doubt, say Y. config CPU_FREQ_GOV_ONDEMAND tristate "'ondemand' cpufreq policy governor" select CPU_FREQ_GOV_COMMON help 'ondemand' - This driver adds a dynamic cpufreq policy governor. The governor does a periodic polling and changes frequency based on the CPU utilization. The support for this governor depends on CPU capability to do fast frequency switching (i.e, very low latency frequency transitions). To compile this driver as a module, choose M here: the module will be called cpufreq_ondemand. For details, take a look at . If in doubt, say N. config CPU_FREQ_GOV_CONSERVATIVE tristate "'conservative' cpufreq governor" depends on CPU_FREQ select CPU_FREQ_GOV_COMMON help 'conservative' - this driver is rather similar to the 'ondemand' governor both in its source code and its purpose, the difference is its optimisation for better suitability in a battery powered environment. The frequency is gracefully increased and decreased rather than jumping to 100% when speed is required. If you have a desktop machine then you should really be considering the 'ondemand' governor instead, however if you are using a laptop, PDA or even an AMD64 based computer (due to the unacceptable step-by-step latency issues between the minimum and maximum frequency transitions in the CPU) you will probably want to use this governor. To compile this driver as a module, choose M here: the module will be called cpufreq_conservative. For details, take a look at . If in doubt, say N. config CPU_FREQ_GOV_SCHEDUTIL bool "'schedutil' cpufreq policy governor" depends on CPU_FREQ && SMP select CPU_FREQ_GOV_ATTR_SET select IRQ_WORK help This governor makes decisions based on the utilization data provided by the scheduler. It sets the CPU frequency to be proportional to the utilization/capacity ratio coming from the scheduler. If the utilization is frequency-invariant, the new frequency is also proportional to the maximum available frequency. If that is not the case, it is proportional to the current frequency of the CPU. The frequency tipping point is at utilization/capacity equal to 80% in both cases. If in doubt, say N. comment "CPU frequency scaling drivers" config CPUFREQ_DT tristate "Generic DT based cpufreq driver" depends on HAVE_CLK && OF select CPUFREQ_DT_PLATDEV select PM_OPP help This adds a generic DT based cpufreq driver for frequency management. It supports both uniprocessor (UP) and symmetric multiprocessor (SMP) systems. If in doubt, say N. config CPUFREQ_VIRT tristate "Virtual cpufreq driver" depends on GENERIC_ARCH_TOPOLOGY help This adds a virtualized cpufreq driver for guest kernels that read/writes to a MMIO region for a virtualized cpufreq device to communicate with the host. It sends performance requests to the host which gets used as a hint to schedule vCPU threads and select CPU frequency. If a VM does not support a virtualized FIE such as AMUs, it updates the frequency scaling factor by polling host CPU frequency to enable accurate Per-Entity Load Tracking for tasks running in the guest. If in doubt, say N. config CPUFREQ_DT_PLATDEV tristate "Generic DT based cpufreq platdev driver" depends on OF help This adds a generic DT based cpufreq platdev driver for frequency management. This creates a 'cpufreq-dt' platform device, on the supported platforms. If in doubt, say N. if X86 source "drivers/cpufreq/Kconfig.x86" endif source "drivers/cpufreq/Kconfig.arm" if PPC32 || PPC64 source "drivers/cpufreq/Kconfig.powerpc" endif if MIPS config BMIPS_CPUFREQ tristate "BMIPS CPUfreq Driver" help This option adds a CPUfreq driver for BMIPS processors with support for configurable CPU frequency. For now, BMIPS5 chips are supported (such as the Broadcom 7425). If in doubt, say N. config LOONGSON2_CPUFREQ tristate "Loongson2 CPUFreq Driver" depends on LEMOTE_MACH2F help This option adds a CPUFreq driver for loongson processors which support software configurable cpu frequency. Loongson2F and its successors support this feature. If in doubt, say N. endif if LOONGARCH config LOONGSON3_CPUFREQ tristate "Loongson3 CPUFreq Driver" help This option adds a CPUFreq driver for Loongson processors which support software configurable cpu frequency. Loongson-3 family processors support this feature. If in doubt, say N. endif if SPARC64 config SPARC_US3_CPUFREQ tristate "UltraSPARC-III CPU Frequency driver" help This adds the CPUFreq driver for UltraSPARC-III processors. If in doubt, say N. config SPARC_US2E_CPUFREQ tristate "UltraSPARC-IIe CPU Frequency driver" help This adds the CPUFreq driver for UltraSPARC-IIe processors. If in doubt, say N. endif if SUPERH config SH_CPU_FREQ tristate "SuperH CPU Frequency driver" help This adds the cpufreq driver for SuperH. Any CPU that supports clock rate rounding through the clock framework can use this driver. While it will make the kernel slightly larger, this is harmless for CPUs that don't support rate rounding. The driver will also generate a notice in the boot log before disabling itself if the CPU in question is not capable of rate rounding. If unsure, say N. endif config QORIQ_CPUFREQ tristate "CPU frequency scaling driver for Freescale QorIQ SoCs" depends on OF && COMMON_CLK depends on PPC_E500MC || SOC_LS1021A || ARCH_LAYERSCAPE || COMPILE_TEST select CLK_QORIQ help This adds the CPUFreq driver support for Freescale QorIQ SoCs which are capable of changing the CPU's frequency dynamically. endif config ACPI_CPPC_CPUFREQ tristate "CPUFreq driver based on the ACPI CPPC spec" depends on ACPI_PROCESSOR depends on ARM || ARM64 || RISCV select ACPI_CPPC_LIB help This adds a CPUFreq driver which uses CPPC methods as described in the ACPIv5.1 spec. CPPC stands for Collaborative Processor Performance Controls. It is based on an abstract continuous scale of CPU performance values which allows the remote power processor to flexibly optimize for power and performance. CPPC relies on power management firmware support for its operation. If in doubt, say N. config ACPI_CPPC_CPUFREQ_FIE bool "Frequency Invariance support for CPPC cpufreq driver" depends on ACPI_CPPC_CPUFREQ && GENERIC_ARCH_TOPOLOGY depends on ARM || ARM64 || RISCV default y help This extends frequency invariance support in the CPPC cpufreq driver, by using CPPC delivered and reference performance counters. If in doubt, say N. endmenu