1 menu "CPU Frequency scaling"
4 bool "CPU Frequency scaling"
7 CPU Frequency scaling allows you to change the clock speed of
8 CPUs on the fly. This is a nice method to save power, because
9 the lower the CPU clock speed, the less power the CPU consumes.
11 Note that this driver doesn't automatically change the CPU
12 clock speed, you need to either enable a dynamic cpufreq governor
13 (see below) after boot, or use a userspace tool.
15 For details, take a look at <file:Documentation/cpu-freq>.
21 config CPU_FREQ_GOV_ATTR_SET
24 config CPU_FREQ_GOV_COMMON
25 select CPU_FREQ_GOV_ATTR_SET
30 bool "CPU frequency transition statistics"
32 Export CPU frequency statistics information through sysfs.
37 prompt "Default CPUFreq governor"
38 default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
39 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
41 This option sets which CPUFreq governor shall be loaded at
42 startup. If in doubt, select 'performance'.
44 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
46 select CPU_FREQ_GOV_PERFORMANCE
48 Use the CPUFreq governor 'performance' as default. This sets
49 the frequency statically to the highest frequency supported by
52 config CPU_FREQ_DEFAULT_GOV_POWERSAVE
54 select CPU_FREQ_GOV_POWERSAVE
56 Use the CPUFreq governor 'powersave' as default. This sets
57 the frequency statically to the lowest frequency supported by
60 config CPU_FREQ_DEFAULT_GOV_USERSPACE
62 select CPU_FREQ_GOV_USERSPACE
64 Use the CPUFreq governor 'userspace' as default. This allows
65 you to set the CPU frequency manually or when a userspace
66 program shall be able to set the CPU dynamically without having
67 to enable the userspace governor manually.
69 config CPU_FREQ_DEFAULT_GOV_ONDEMAND
71 select CPU_FREQ_GOV_ONDEMAND
72 select CPU_FREQ_GOV_PERFORMANCE
74 Use the CPUFreq governor 'ondemand' as default. This allows
75 you to get a full dynamic frequency capable system by simply
76 loading your cpufreq low-level hardware driver.
77 Be aware that not all cpufreq drivers support the ondemand
78 governor. If unsure have a look at the help section of the
79 driver. Fallback governor will be the performance governor.
81 config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
83 select CPU_FREQ_GOV_CONSERVATIVE
84 select CPU_FREQ_GOV_PERFORMANCE
86 Use the CPUFreq governor 'conservative' as default. This allows
87 you to get a full dynamic frequency capable system by simply
88 loading your cpufreq low-level hardware driver.
89 Be aware that not all cpufreq drivers support the conservative
90 governor. If unsure have a look at the help section of the
91 driver. Fallback governor will be the performance governor.
93 config CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
96 select CPU_FREQ_GOV_SCHEDUTIL
97 select CPU_FREQ_GOV_PERFORMANCE
99 Use the 'schedutil' CPUFreq governor by default. If unsure,
100 have a look at the help section of that governor. The fallback
101 governor will be 'performance'.
105 config CPU_FREQ_GOV_PERFORMANCE
106 tristate "'performance' governor"
108 This cpufreq governor sets the frequency statically to the
109 highest available CPU frequency.
111 To compile this driver as a module, choose M here: the
112 module will be called cpufreq_performance.
116 config CPU_FREQ_GOV_POWERSAVE
117 tristate "'powersave' governor"
119 This cpufreq governor sets the frequency statically to the
120 lowest available CPU frequency.
122 To compile this driver as a module, choose M here: the
123 module will be called cpufreq_powersave.
127 config CPU_FREQ_GOV_USERSPACE
128 tristate "'userspace' governor for userspace frequency scaling"
130 Enable this cpufreq governor when you either want to set the
131 CPU frequency manually or when a userspace program shall
132 be able to set the CPU dynamically, like on LART
133 <http://www.lartmaker.nl/>.
135 To compile this driver as a module, choose M here: the
136 module will be called cpufreq_userspace.
138 For details, take a look at <file:Documentation/cpu-freq/>.
142 config CPU_FREQ_GOV_ONDEMAND
143 tristate "'ondemand' cpufreq policy governor"
144 select CPU_FREQ_GOV_COMMON
146 'ondemand' - This driver adds a dynamic cpufreq policy governor.
147 The governor does a periodic polling and
148 changes frequency based on the CPU utilization.
149 The support for this governor depends on CPU capability to
150 do fast frequency switching (i.e, very low latency frequency
153 To compile this driver as a module, choose M here: the
154 module will be called cpufreq_ondemand.
156 For details, take a look at linux/Documentation/cpu-freq.
160 config CPU_FREQ_GOV_CONSERVATIVE
161 tristate "'conservative' cpufreq governor"
163 select CPU_FREQ_GOV_COMMON
165 'conservative' - this driver is rather similar to the 'ondemand'
166 governor both in its source code and its purpose, the difference is
167 its optimisation for better suitability in a battery powered
168 environment. The frequency is gracefully increased and decreased
169 rather than jumping to 100% when speed is required.
171 If you have a desktop machine then you should really be considering
172 the 'ondemand' governor instead, however if you are using a laptop,
173 PDA or even an AMD64 based computer (due to the unacceptable
174 step-by-step latency issues between the minimum and maximum frequency
175 transitions in the CPU) you will probably want to use this governor.
177 To compile this driver as a module, choose M here: the
178 module will be called cpufreq_conservative.
180 For details, take a look at linux/Documentation/cpu-freq.
184 config CPU_FREQ_GOV_SCHEDUTIL
185 bool "'schedutil' cpufreq policy governor"
186 depends on CPU_FREQ && SMP
187 select CPU_FREQ_GOV_ATTR_SET
190 This governor makes decisions based on the utilization data provided
191 by the scheduler. It sets the CPU frequency to be proportional to
192 the utilization/capacity ratio coming from the scheduler. If the
193 utilization is frequency-invariant, the new frequency is also
194 proportional to the maximum available frequency. If that is not the
195 case, it is proportional to the current frequency of the CPU. The
196 frequency tipping point is at utilization/capacity equal to 80% in
201 comment "CPU frequency scaling drivers"
204 tristate "Generic DT based cpufreq driver"
205 depends on HAVE_CLK && OF
206 select CPUFREQ_DT_PLATDEV
209 This adds a generic DT based cpufreq driver for frequency management.
210 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
215 config CPUFREQ_DT_PLATDEV
218 This adds a generic DT based cpufreq platdev driver for frequency
219 management. This creates a 'cpufreq-dt' platform device, on the
225 source "drivers/cpufreq/Kconfig.x86"
229 source "drivers/cpufreq/Kconfig.arm"
233 source "drivers/cpufreq/Kconfig.powerpc"
237 config IA64_ACPI_CPUFREQ
238 tristate "ACPI Processor P-States driver"
239 depends on ACPI_PROCESSOR
241 This driver adds a CPUFreq driver which utilizes the ACPI
242 Processor Performance States.
244 For details, take a look at <file:Documentation/cpu-freq/>.
251 tristate "BMIPS CPUfreq Driver"
253 This option adds a CPUfreq driver for BMIPS processors with
254 support for configurable CPU frequency.
256 For now, BMIPS5 chips are supported (such as the Broadcom 7425).
260 config LOONGSON2_CPUFREQ
261 tristate "Loongson2 CPUFreq Driver"
262 depends on LEMOTE_MACH2F
264 This option adds a CPUFreq driver for loongson processors which
265 support software configurable cpu frequency.
267 Loongson2F and it's successors support this feature.
269 For details, take a look at <file:Documentation/cpu-freq/>.
273 config LOONGSON1_CPUFREQ
274 tristate "Loongson1 CPUFreq Driver"
275 depends on LOONGSON1_LS1B
277 This option adds a CPUFreq driver for loongson1 processors which
278 support software configurable cpu frequency.
280 For details, take a look at <file:Documentation/cpu-freq/>.
286 config SPARC_US3_CPUFREQ
287 tristate "UltraSPARC-III CPU Frequency driver"
289 This adds the CPUFreq driver for UltraSPARC-III processors.
291 For details, take a look at <file:Documentation/cpu-freq>.
295 config SPARC_US2E_CPUFREQ
296 tristate "UltraSPARC-IIe CPU Frequency driver"
298 This adds the CPUFreq driver for UltraSPARC-IIe processors.
300 For details, take a look at <file:Documentation/cpu-freq>.
307 tristate "SuperH CPU Frequency driver"
309 This adds the cpufreq driver for SuperH. Any CPU that supports
310 clock rate rounding through the clock framework can use this
311 driver. While it will make the kernel slightly larger, this is
312 harmless for CPUs that don't support rate rounding. The driver
313 will also generate a notice in the boot log before disabling
314 itself if the CPU in question is not capable of rate rounding.
316 For details, take a look at <file:Documentation/cpu-freq>.
322 tristate "CPU frequency scaling driver for Freescale QorIQ SoCs"
323 depends on OF && COMMON_CLK && (PPC_E500MC || ARM || ARM64)
326 This adds the CPUFreq driver support for Freescale QorIQ SoCs
327 which are capable of changing the CPU's frequency dynamically.