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_COMMON
24 config CPU_FREQ_BOOST_SW
29 tristate "CPU frequency translation statistics"
32 This driver exports CPU frequency statistics information through sysfs
35 To compile this driver as a module, choose M here: the
36 module will be called cpufreq_stats.
40 config CPU_FREQ_STAT_DETAILS
41 bool "CPU frequency translation statistics details"
42 depends on CPU_FREQ_STAT
44 This will show detail CPU frequency translation table in sysfs file
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_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_GOV_COMMON
158 'ondemand' - This driver adds a dynamic cpufreq policy governor.
159 The governor does a periodic polling and
160 changes frequency based on the CPU utilization.
161 The support for this governor depends on CPU capability to
162 do fast frequency switching (i.e, very low latency frequency
165 To compile this driver as a module, choose M here: the
166 module will be called cpufreq_ondemand.
168 For details, take a look at linux/Documentation/cpu-freq.
172 config CPU_FREQ_GOV_INTERACTIVE
173 tristate "'interactive' cpufreq policy governor"
175 'interactive' - This driver adds a dynamic cpufreq policy governor
176 designed for latency-sensitive workloads.
178 This governor attempts to reduce the latency of clock
179 increases so that the system is more responsive to
180 interactive workloads.
182 To compile this driver as a module, choose M here: the
183 module will be called cpufreq_interactive.
185 For details, take a look at linux/Documentation/cpu-freq.
189 config CPU_FREQ_GOV_CONSERVATIVE
190 tristate "'conservative' cpufreq governor"
192 select CPU_FREQ_GOV_COMMON
194 'conservative' - this driver is rather similar to the 'ondemand'
195 governor both in its source code and its purpose, the difference is
196 its optimisation for better suitability in a battery powered
197 environment. The frequency is gracefully increased and decreased
198 rather than jumping to 100% when speed is required.
200 If you have a desktop machine then you should really be considering
201 the 'ondemand' governor instead, however if you are using a laptop,
202 PDA or even an AMD64 based computer (due to the unacceptable
203 step-by-step latency issues between the minimum and maximum frequency
204 transitions in the CPU) you will probably want to use this governor.
206 To compile this driver as a module, choose M here: the
207 module will be called cpufreq_conservative.
209 For details, take a look at linux/Documentation/cpu-freq.
213 comment "CPU frequency scaling drivers"
216 tristate "Generic DT based cpufreq driver"
217 depends on HAVE_CLK && OF
218 # if CPU_THERMAL is on and THERMAL=m, CPUFREQ_DT cannot be =y:
219 depends on !CPU_THERMAL || THERMAL
222 This adds a generic DT based cpufreq driver for frequency management.
223 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
224 systems which share clock and voltage across all CPUs.
229 source "drivers/cpufreq/Kconfig.x86"
233 source "drivers/cpufreq/Kconfig.arm"
237 source "drivers/cpufreq/Kconfig.powerpc"
241 config AVR32_AT32AP_CPUFREQ
242 bool "CPU frequency driver for AT32AP"
243 depends on PLATFORM_AT32AP
246 This enables the CPU frequency driver for AT32AP processors.
251 config IA64_ACPI_CPUFREQ
252 tristate "ACPI Processor P-States driver"
253 depends on ACPI_PROCESSOR
255 This driver adds a CPUFreq driver which utilizes the ACPI
256 Processor Performance States.
258 For details, take a look at <file:Documentation/cpu-freq/>.
264 config LOONGSON2_CPUFREQ
265 tristate "Loongson2 CPUFreq Driver"
267 This option adds a CPUFreq driver for loongson processors which
268 support software configurable cpu frequency.
270 Loongson2F and it's successors support this feature.
272 For details, take a look at <file:Documentation/cpu-freq/>.
276 config LOONGSON1_CPUFREQ
277 tristate "Loongson1 CPUFreq Driver"
279 This option adds a CPUFreq driver for loongson1 processors which
280 support software configurable cpu frequency.
282 For details, take a look at <file:Documentation/cpu-freq/>.
288 config SPARC_US3_CPUFREQ
289 tristate "UltraSPARC-III CPU Frequency driver"
291 This adds the CPUFreq driver for UltraSPARC-III processors.
293 For details, take a look at <file:Documentation/cpu-freq>.
297 config SPARC_US2E_CPUFREQ
298 tristate "UltraSPARC-IIe CPU Frequency driver"
300 This adds the CPUFreq driver for UltraSPARC-IIe processors.
302 For details, take a look at <file:Documentation/cpu-freq>.
309 tristate "SuperH CPU Frequency driver"
311 This adds the cpufreq driver for SuperH. Any CPU that supports
312 clock rate rounding through the clock framework can use this
313 driver. While it will make the kernel slightly larger, this is
314 harmless for CPUs that don't support rate rounding. The driver
315 will also generate a notice in the boot log before disabling
316 itself if the CPU in question is not capable of rate rounding.
318 For details, take a look at <file:Documentation/cpu-freq>.
324 tristate "CPU frequency scaling driver for Freescale QorIQ SoCs"
325 depends on OF && COMMON_CLK && (PPC_E500MC || ARM)
328 This adds the CPUFreq driver support for Freescale QorIQ SoCs
329 which are capable of changing the CPU's frequency dynamically.