1 menu "CPU Frequency scaling"
4 bool "CPU Frequency scaling"
6 CPU Frequency scaling allows you to change the clock speed of
7 CPUs on the fly. This is a nice method to save power, because
8 the lower the CPU clock speed, the less power the CPU consumes.
10 Note that this driver doesn't automatically change the CPU
11 clock speed, you need to either enable a dynamic cpufreq governor
12 (see below) after boot, or use a userspace tool.
14 For details, take a look at <file:Documentation/cpu-freq>.
23 config CPU_FREQ_GOV_COMMON
27 tristate "CPU frequency translation statistics"
31 This driver exports CPU frequency statistics information through sysfs
34 To compile this driver as a module, choose M here: the
35 module will be called cpufreq_stats.
39 config CPU_FREQ_STAT_DETAILS
40 bool "CPU frequency translation statistics details"
41 depends on CPU_FREQ_STAT
43 This will show detail CPU frequency translation table in sysfs file
49 prompt "Default CPUFreq governor"
50 default CPU_FREQ_DEFAULT_GOV_USERSPACE if ARM_SA1100_CPUFREQ || ARM_SA1110_CPUFREQ
51 default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
53 This option sets which CPUFreq governor shall be loaded at
54 startup. If in doubt, select 'performance'.
56 config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
58 select CPU_FREQ_GOV_PERFORMANCE
60 Use the CPUFreq governor 'performance' as default. This sets
61 the frequency statically to the highest frequency supported by
64 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_INTERACTIVE
108 select CPU_FREQ_GOV_INTERACTIVE
110 Use the CPUFreq governor 'interactive' as default. This allows
111 you to get a full dynamic cpu frequency capable system by simply
112 loading your cpufreq low-level hardware driver, using the
113 'interactive' governor for latency-sensitive workloads.
117 config CPU_FREQ_GOV_PERFORMANCE
118 tristate "'performance' governor"
120 This cpufreq governor sets the frequency statically to the
121 highest available CPU frequency.
123 To compile this driver as a module, choose M here: the
124 module will be called cpufreq_performance.
128 config CPU_FREQ_GOV_POWERSAVE
129 tristate "'powersave' governor"
131 This cpufreq governor sets the frequency statically to the
132 lowest available CPU frequency.
134 To compile this driver as a module, choose M here: the
135 module will be called cpufreq_powersave.
139 config CPU_FREQ_GOV_USERSPACE
140 tristate "'userspace' governor for userspace frequency scaling"
142 Enable this cpufreq governor when you either want to set the
143 CPU frequency manually or when a userspace program shall
144 be able to set the CPU dynamically, like on LART
145 <http://www.lartmaker.nl/>.
147 To compile this driver as a module, choose M here: the
148 module will be called cpufreq_userspace.
150 For details, take a look at <file:Documentation/cpu-freq/>.
154 config CPU_FREQ_GOV_ONDEMAND
155 tristate "'ondemand' cpufreq policy governor"
156 select CPU_FREQ_TABLE
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_INTERACTIVE
174 tristate "'interactive' cpufreq policy governor"
177 'interactive' - This driver adds a dynamic cpufreq policy governor
178 designed for latency-sensitive workloads.
180 This governor attempts to reduce the latency of clock
181 increases so that the system is more responsive to
182 interactive workloads.
184 To compile this driver as a module, choose M here: the
185 module will be called cpufreq_interactive.
187 For details, take a look at linux/Documentation/cpu-freq.
191 config CPU_FREQ_GOV_CONSERVATIVE
192 tristate "'conservative' cpufreq governor"
194 select CPU_FREQ_GOV_COMMON
196 'conservative' - this driver is rather similar to the 'ondemand'
197 governor both in its source code and its purpose, the difference is
198 its optimisation for better suitability in a battery powered
199 environment. The frequency is gracefully increased and decreased
200 rather than jumping to 100% when speed is required.
202 If you have a desktop machine then you should really be considering
203 the 'ondemand' governor instead, however if you are using a laptop,
204 PDA or even an AMD64 based computer (due to the unacceptable
205 step-by-step latency issues between the minimum and maximum frequency
206 transitions in the CPU) you will probably want to use this governor.
208 To compile this driver as a module, choose M here: the
209 module will be called cpufreq_conservative.
211 For details, take a look at linux/Documentation/cpu-freq.
215 config GENERIC_CPUFREQ_CPU0
216 tristate "Generic CPU0 cpufreq driver"
217 depends on HAVE_CLK && REGULATOR && PM_OPP && OF
218 select CPU_FREQ_TABLE
220 This adds a generic cpufreq driver for CPU0 frequency management.
221 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
222 systems which share clock and voltage across all CPUs.
226 menu "x86 CPU frequency scaling drivers"
228 source "drivers/cpufreq/Kconfig.x86"
231 menu "ARM CPU frequency scaling drivers"
233 source "drivers/cpufreq/Kconfig.arm"
236 menu "AVR32 CPU frequency scaling drivers"
239 config AVR32_AT32AP_CPUFREQ
240 bool "CPU frequency driver for AT32AP"
241 depends on PLATFORM_AT32AP
244 This enables the CPU frequency driver for AT32AP processors.
249 menu "CPUFreq processor drivers"
252 config IA64_ACPI_CPUFREQ
253 tristate "ACPI Processor P-States driver"
254 select CPU_FREQ_TABLE
255 depends on ACPI_PROCESSOR
257 This driver adds a CPUFreq driver which utilizes the ACPI
258 Processor Performance States.
260 For details, take a look at <file:Documentation/cpu-freq/>.
266 menu "MIPS CPUFreq processor drivers"
269 config LOONGSON2_CPUFREQ
270 tristate "Loongson2 CPUFreq Driver"
271 select CPU_FREQ_TABLE
273 This option adds a CPUFreq driver for loongson processors which
274 support software configurable cpu frequency.
276 Loongson2F and it's successors support this feature.
278 For details, take a look at <file:Documentation/cpu-freq/>.
284 menu "PowerPC CPU frequency scaling drivers"
285 depends on PPC32 || PPC64
286 source "drivers/cpufreq/Kconfig.powerpc"
289 menu "SPARC CPU frequency scaling drivers"
291 config SPARC_US3_CPUFREQ
292 tristate "UltraSPARC-III CPU Frequency driver"
293 select CPU_FREQ_TABLE
295 This adds the CPUFreq driver for UltraSPARC-III processors.
297 For details, take a look at <file:Documentation/cpu-freq>.
301 config SPARC_US2E_CPUFREQ
302 tristate "UltraSPARC-IIe CPU Frequency driver"
303 select CPU_FREQ_TABLE
305 This adds the CPUFreq driver for UltraSPARC-IIe processors.
307 For details, take a look at <file:Documentation/cpu-freq>.
312 menu "SH CPU Frequency scaling"
315 tristate "SuperH CPU Frequency driver"
316 select CPU_FREQ_TABLE
318 This adds the cpufreq driver for SuperH. Any CPU that supports
319 clock rate rounding through the clock framework can use this
320 driver. While it will make the kernel slightly larger, this is
321 harmless for CPUs that don't support rate rounding. The driver
322 will also generate a notice in the boot log before disabling
323 itself if the CPU in question is not capable of rate rounding.
325 For details, take a look at <file:Documentation/cpu-freq>.