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
29 config CPU_FREQ_BOOST_SW
34 bool "CPU frequency transition statistics"
37 Export CPU frequency statistics information through sysfs.
41 config CPU_FREQ_STAT_DETAILS
42 bool "CPU frequency transition statistics details"
43 depends on CPU_FREQ_STAT
45 Show detailed CPU frequency transition table in sysfs.
50 prompt "Default CPUFreq governor"
51 default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
52 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
54 This option sets which CPUFreq governor shall be loaded at
55 startup. If in doubt, select 'performance'.
57 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
59 select CPU_FREQ_GOV_PERFORMANCE
61 Use the CPUFreq governor 'performance' as default. This sets
62 the frequency statically to the highest frequency supported by
65 config CPU_FREQ_DEFAULT_GOV_POWERSAVE
67 select CPU_FREQ_GOV_POWERSAVE
69 Use the CPUFreq governor 'powersave' as default. This sets
70 the frequency statically to the lowest frequency supported by
73 config CPU_FREQ_DEFAULT_GOV_USERSPACE
75 select CPU_FREQ_GOV_USERSPACE
77 Use the CPUFreq governor 'userspace' as default. This allows
78 you to set the CPU frequency manually or when a userspace
79 program shall be able to set the CPU dynamically without having
80 to enable the userspace governor manually.
82 config CPU_FREQ_DEFAULT_GOV_ONDEMAND
84 select CPU_FREQ_GOV_ONDEMAND
85 select CPU_FREQ_GOV_PERFORMANCE
87 Use the CPUFreq governor 'ondemand' as default. This allows
88 you to get a full dynamic frequency capable system by simply
89 loading your cpufreq low-level hardware driver.
90 Be aware that not all cpufreq drivers support the ondemand
91 governor. If unsure have a look at the help section of the
92 driver. Fallback governor will be the performance governor.
94 config CPU_FREQ_DEFAULT_GOV_CONSERVATIVE
96 select CPU_FREQ_GOV_CONSERVATIVE
97 select CPU_FREQ_GOV_PERFORMANCE
99 Use the CPUFreq governor 'conservative' as default. This allows
100 you to get a full dynamic frequency capable system by simply
101 loading your cpufreq low-level hardware driver.
102 Be aware that not all cpufreq drivers support the conservative
103 governor. If unsure have a look at the help section of the
104 driver. Fallback governor will be the performance governor.
106 config CPU_FREQ_DEFAULT_GOV_SCHEDUTIL
109 select CPU_FREQ_GOV_SCHEDUTIL
110 select CPU_FREQ_GOV_PERFORMANCE
112 Use the 'schedutil' CPUFreq governor by default. If unsure,
113 have a look at the help section of that governor. The fallback
114 governor will be 'performance'.
118 config CPU_FREQ_GOV_PERFORMANCE
119 tristate "'performance' governor"
121 This cpufreq governor sets the frequency statically to the
122 highest available CPU frequency.
124 To compile this driver as a module, choose M here: the
125 module will be called cpufreq_performance.
129 config CPU_FREQ_GOV_POWERSAVE
130 tristate "'powersave' governor"
132 This cpufreq governor sets the frequency statically to the
133 lowest available CPU frequency.
135 To compile this driver as a module, choose M here: the
136 module will be called cpufreq_powersave.
140 config CPU_FREQ_GOV_USERSPACE
141 tristate "'userspace' governor for userspace frequency scaling"
143 Enable this cpufreq governor when you either want to set the
144 CPU frequency manually or when a userspace program shall
145 be able to set the CPU dynamically, like on LART
146 <http://www.lartmaker.nl/>.
148 To compile this driver as a module, choose M here: the
149 module will be called cpufreq_userspace.
151 For details, take a look at <file:Documentation/cpu-freq/>.
155 config CPU_FREQ_GOV_ONDEMAND
156 tristate "'ondemand' cpufreq policy governor"
157 select CPU_FREQ_GOV_COMMON
159 'ondemand' - This driver adds a dynamic cpufreq policy governor.
160 The governor does a periodic polling and
161 changes frequency based on the CPU utilization.
162 The support for this governor depends on CPU capability to
163 do fast frequency switching (i.e, very low latency frequency
166 To compile this driver as a module, choose M here: the
167 module will be called cpufreq_ondemand.
169 For details, take a look at linux/Documentation/cpu-freq.
173 config CPU_FREQ_GOV_CONSERVATIVE
174 tristate "'conservative' cpufreq governor"
176 select CPU_FREQ_GOV_COMMON
178 'conservative' - this driver is rather similar to the 'ondemand'
179 governor both in its source code and its purpose, the difference is
180 its optimisation for better suitability in a battery powered
181 environment. The frequency is gracefully increased and decreased
182 rather than jumping to 100% when speed is required.
184 If you have a desktop machine then you should really be considering
185 the 'ondemand' governor instead, however if you are using a laptop,
186 PDA or even an AMD64 based computer (due to the unacceptable
187 step-by-step latency issues between the minimum and maximum frequency
188 transitions in the CPU) you will probably want to use this governor.
190 To compile this driver as a module, choose M here: the
191 module will be called cpufreq_conservative.
193 For details, take a look at linux/Documentation/cpu-freq.
197 config CPU_FREQ_GOV_SCHEDUTIL
198 tristate "'schedutil' cpufreq policy governor"
199 depends on CPU_FREQ && SMP
200 select CPU_FREQ_GOV_ATTR_SET
203 This governor makes decisions based on the utilization data provided
204 by the scheduler. It sets the CPU frequency to be proportional to
205 the utilization/capacity ratio coming from the scheduler. If the
206 utilization is frequency-invariant, the new frequency is also
207 proportional to the maximum available frequency. If that is not the
208 case, it is proportional to the current frequency of the CPU. The
209 frequency tipping point is at utilization/capacity equal to 80% in
212 To compile this driver as a module, choose M here: the module will
213 be called cpufreq_schedutil.
217 comment "CPU frequency scaling drivers"
220 tristate "Generic DT based cpufreq driver"
221 depends on HAVE_CLK && OF
222 # if CPU_THERMAL is on and THERMAL=m, CPUFREQ_DT cannot be =y:
223 depends on !CPU_THERMAL || THERMAL
224 select CPUFREQ_DT_PLATDEV
227 This adds a generic DT based cpufreq driver for frequency management.
228 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
229 systems which share clock and voltage across all CPUs.
233 config CPUFREQ_DT_PLATDEV
236 This adds a generic DT based cpufreq platdev driver for frequency
237 management. This creates a 'cpufreq-dt' platform device, on the
243 source "drivers/cpufreq/Kconfig.x86"
247 source "drivers/cpufreq/Kconfig.arm"
251 source "drivers/cpufreq/Kconfig.powerpc"
255 config AVR32_AT32AP_CPUFREQ
256 bool "CPU frequency driver for AT32AP"
257 depends on PLATFORM_AT32AP
260 This enables the CPU frequency driver for AT32AP processors.
265 config IA64_ACPI_CPUFREQ
266 tristate "ACPI Processor P-States driver"
267 depends on ACPI_PROCESSOR
269 This driver adds a CPUFreq driver which utilizes the ACPI
270 Processor Performance States.
272 For details, take a look at <file:Documentation/cpu-freq/>.
278 config LOONGSON2_CPUFREQ
279 tristate "Loongson2 CPUFreq Driver"
281 This option adds a CPUFreq driver for loongson processors which
282 support software configurable cpu frequency.
284 Loongson2F and it's successors support this feature.
286 For details, take a look at <file:Documentation/cpu-freq/>.
290 config LOONGSON1_CPUFREQ
291 tristate "Loongson1 CPUFreq Driver"
293 This option adds a CPUFreq driver for loongson1 processors which
294 support software configurable cpu frequency.
296 For details, take a look at <file:Documentation/cpu-freq/>.
302 config SPARC_US3_CPUFREQ
303 tristate "UltraSPARC-III CPU Frequency driver"
305 This adds the CPUFreq driver for UltraSPARC-III processors.
307 For details, take a look at <file:Documentation/cpu-freq>.
311 config SPARC_US2E_CPUFREQ
312 tristate "UltraSPARC-IIe CPU Frequency driver"
314 This adds the CPUFreq driver for UltraSPARC-IIe processors.
316 For details, take a look at <file:Documentation/cpu-freq>.
323 tristate "SuperH CPU Frequency driver"
325 This adds the cpufreq driver for SuperH. Any CPU that supports
326 clock rate rounding through the clock framework can use this
327 driver. While it will make the kernel slightly larger, this is
328 harmless for CPUs that don't support rate rounding. The driver
329 will also generate a notice in the boot log before disabling
330 itself if the CPU in question is not capable of rate rounding.
332 For details, take a look at <file:Documentation/cpu-freq>.
338 tristate "CPU frequency scaling driver for Freescale QorIQ SoCs"
339 depends on OF && COMMON_CLK && (PPC_E500MC || ARM)
340 depends on !CPU_THERMAL || THERMAL
343 This adds the CPUFreq driver support for Freescale QorIQ SoCs
344 which are capable of changing the CPU's frequency dynamically.