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"
176 'interactive' - This driver adds a dynamic cpufreq policy governor
177 designed for latency-sensitive workloads.
179 This governor attempts to reduce the latency of clock
180 increases so that the system is more responsive to
181 interactive workloads.
183 To compile this driver as a module, choose M here: the
184 module will be called cpufreq_interactive.
186 For details, take a look at linux/Documentation/cpu-freq.
190 config CPU_FREQ_GOV_CONSERVATIVE
191 tristate "'conservative' cpufreq governor"
193 select CPU_FREQ_GOV_COMMON
195 'conservative' - this driver is rather similar to the 'ondemand'
196 governor both in its source code and its purpose, the difference is
197 its optimisation for better suitability in a battery powered
198 environment. The frequency is gracefully increased and decreased
199 rather than jumping to 100% when speed is required.
201 If you have a desktop machine then you should really be considering
202 the 'ondemand' governor instead, however if you are using a laptop,
203 PDA or even an AMD64 based computer (due to the unacceptable
204 step-by-step latency issues between the minimum and maximum frequency
205 transitions in the CPU) you will probably want to use this governor.
207 To compile this driver as a module, choose M here: the
208 module will be called cpufreq_conservative.
210 For details, take a look at linux/Documentation/cpu-freq.
214 config GENERIC_CPUFREQ_CPU0
215 tristate "Generic CPU0 cpufreq driver"
216 depends on HAVE_CLK && REGULATOR && PM_OPP && OF
217 select CPU_FREQ_TABLE
219 This adds a generic cpufreq driver for CPU0 frequency management.
220 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
221 systems which share clock and voltage across all CPUs.
225 menu "x86 CPU frequency scaling drivers"
227 source "drivers/cpufreq/Kconfig.x86"
230 menu "ARM CPU frequency scaling drivers"
232 source "drivers/cpufreq/Kconfig.arm"
235 menu "AVR32 CPU frequency scaling drivers"
238 config AVR32_AT32AP_CPUFREQ
239 bool "CPU frequency driver for AT32AP"
240 depends on PLATFORM_AT32AP
243 This enables the CPU frequency driver for AT32AP processors.
248 menu "CPUFreq processor drivers"
251 config IA64_ACPI_CPUFREQ
252 tristate "ACPI Processor P-States driver"
253 select CPU_FREQ_TABLE
254 depends on ACPI_PROCESSOR
256 This driver adds a CPUFreq driver which utilizes the ACPI
257 Processor Performance States.
259 For details, take a look at <file:Documentation/cpu-freq/>.
265 menu "MIPS CPUFreq processor drivers"
268 config LOONGSON2_CPUFREQ
269 tristate "Loongson2 CPUFreq Driver"
270 select CPU_FREQ_TABLE
272 This option adds a CPUFreq driver for loongson processors which
273 support software configurable cpu frequency.
275 Loongson2F and it's successors support this feature.
277 For details, take a look at <file:Documentation/cpu-freq/>.
283 menu "PowerPC CPU frequency scaling drivers"
284 depends on PPC32 || PPC64
285 source "drivers/cpufreq/Kconfig.powerpc"
288 menu "SPARC CPU frequency scaling drivers"
290 config SPARC_US3_CPUFREQ
291 tristate "UltraSPARC-III CPU Frequency driver"
292 select CPU_FREQ_TABLE
294 This adds the CPUFreq driver for UltraSPARC-III processors.
296 For details, take a look at <file:Documentation/cpu-freq>.
300 config SPARC_US2E_CPUFREQ
301 tristate "UltraSPARC-IIe CPU Frequency driver"
302 select CPU_FREQ_TABLE
304 This adds the CPUFreq driver for UltraSPARC-IIe processors.
306 For details, take a look at <file:Documentation/cpu-freq>.
311 menu "SH CPU Frequency scaling"
314 tristate "SuperH CPU Frequency driver"
315 select CPU_FREQ_TABLE
317 This adds the cpufreq driver for SuperH. Any CPU that supports
318 clock rate rounding through the clock framework can use this
319 driver. While it will make the kernel slightly larger, this is
320 harmless for CPUs that don't support rate rounding. The driver
321 will also generate a notice in the boot log before disabling
322 itself if the CPU in question is not capable of rate rounding.
324 For details, take a look at <file:Documentation/cpu-freq>.