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_SCHED
108 select CPU_FREQ_GOV_SCHED
110 Use the CPUfreq governor 'sched' as default. This scales
111 cpu frequency using CPU utilization estimates from the
115 config CPU_FREQ_GOV_PERFORMANCE
116 tristate "'performance' governor"
118 This cpufreq governor sets the frequency statically to the
119 highest available CPU frequency.
121 To compile this driver as a module, choose M here: the
122 module will be called cpufreq_performance.
126 config CPU_FREQ_GOV_POWERSAVE
127 tristate "'powersave' governor"
129 This cpufreq governor sets the frequency statically to the
130 lowest available CPU frequency.
132 To compile this driver as a module, choose M here: the
133 module will be called cpufreq_powersave.
137 config CPU_FREQ_GOV_USERSPACE
138 tristate "'userspace' governor for userspace frequency scaling"
140 Enable this cpufreq governor when you either want to set the
141 CPU frequency manually or when a userspace program shall
142 be able to set the CPU dynamically, like on LART
143 <http://www.lartmaker.nl/>.
145 To compile this driver as a module, choose M here: the
146 module will be called cpufreq_userspace.
148 For details, take a look at <file:Documentation/cpu-freq/>.
152 config CPU_FREQ_GOV_ONDEMAND
153 tristate "'ondemand' cpufreq policy governor"
154 select CPU_FREQ_GOV_COMMON
156 'ondemand' - This driver adds a dynamic cpufreq policy governor.
157 The governor does a periodic polling and
158 changes frequency based on the CPU utilization.
159 The support for this governor depends on CPU capability to
160 do fast frequency switching (i.e, very low latency frequency
163 To compile this driver as a module, choose M here: the
164 module will be called cpufreq_ondemand.
166 For details, take a look at linux/Documentation/cpu-freq.
170 config CPU_FREQ_GOV_CONSERVATIVE
171 tristate "'conservative' cpufreq governor"
173 select CPU_FREQ_GOV_COMMON
175 'conservative' - this driver is rather similar to the 'ondemand'
176 governor both in its source code and its purpose, the difference is
177 its optimisation for better suitability in a battery powered
178 environment. The frequency is gracefully increased and decreased
179 rather than jumping to 100% when speed is required.
181 If you have a desktop machine then you should really be considering
182 the 'ondemand' governor instead, however if you are using a laptop,
183 PDA or even an AMD64 based computer (due to the unacceptable
184 step-by-step latency issues between the minimum and maximum frequency
185 transitions in the CPU) you will probably want to use this governor.
187 To compile this driver as a module, choose M here: the
188 module will be called cpufreq_conservative.
190 For details, take a look at linux/Documentation/cpu-freq.
194 config CPU_FREQ_GOV_SCHED
195 bool "'sched' cpufreq governor"
197 select CPU_FREQ_GOV_COMMON
199 'sched' - this governor scales cpu frequency from the
200 scheduler as a function of cpu capacity utilization. It does
201 not evaluate utilization on a periodic basis (as ondemand
202 does) but instead is event-driven by the scheduler.
206 comment "CPU frequency scaling drivers"
209 tristate "Generic DT based cpufreq driver"
210 depends on HAVE_CLK && OF
211 # if CPU_THERMAL is on and THERMAL=m, CPUFREQ_DT cannot be =y:
212 depends on !CPU_THERMAL || THERMAL
215 This adds a generic DT based cpufreq driver for frequency management.
216 It supports both uniprocessor (UP) and symmetric multiprocessor (SMP)
217 systems which share clock and voltage across all CPUs.
222 source "drivers/cpufreq/Kconfig.x86"
226 source "drivers/cpufreq/Kconfig.arm"
230 source "drivers/cpufreq/Kconfig.powerpc"
234 config AVR32_AT32AP_CPUFREQ
235 bool "CPU frequency driver for AT32AP"
236 depends on PLATFORM_AT32AP
239 This enables the CPU frequency driver for AT32AP processors.
244 config IA64_ACPI_CPUFREQ
245 tristate "ACPI Processor P-States driver"
246 depends on ACPI_PROCESSOR
248 This driver adds a CPUFreq driver which utilizes the ACPI
249 Processor Performance States.
251 For details, take a look at <file:Documentation/cpu-freq/>.
257 config LOONGSON2_CPUFREQ
258 tristate "Loongson2 CPUFreq Driver"
260 This option adds a CPUFreq driver for loongson processors which
261 support software configurable cpu frequency.
263 Loongson2F and it's successors support this feature.
265 For details, take a look at <file:Documentation/cpu-freq/>.
269 config LOONGSON1_CPUFREQ
270 tristate "Loongson1 CPUFreq Driver"
272 This option adds a CPUFreq driver for loongson1 processors which
273 support software configurable cpu frequency.
275 For details, take a look at <file:Documentation/cpu-freq/>.
281 config SPARC_US3_CPUFREQ
282 tristate "UltraSPARC-III CPU Frequency driver"
284 This adds the CPUFreq driver for UltraSPARC-III processors.
286 For details, take a look at <file:Documentation/cpu-freq>.
290 config SPARC_US2E_CPUFREQ
291 tristate "UltraSPARC-IIe CPU Frequency driver"
293 This adds the CPUFreq driver for UltraSPARC-IIe processors.
295 For details, take a look at <file:Documentation/cpu-freq>.
302 tristate "SuperH CPU Frequency driver"
304 This adds the cpufreq driver for SuperH. Any CPU that supports
305 clock rate rounding through the clock framework can use this
306 driver. While it will make the kernel slightly larger, this is
307 harmless for CPUs that don't support rate rounding. The driver
308 will also generate a notice in the boot log before disabling
309 itself if the CPU in question is not capable of rate rounding.
311 For details, take a look at <file:Documentation/cpu-freq>.
317 tristate "CPU frequency scaling driver for Freescale QorIQ SoCs"
318 depends on OF && COMMON_CLK && (PPC_E500MC || ARM)
321 This adds the CPUFreq driver support for Freescale QorIQ SoCs
322 which are capable of changing the CPU's frequency dynamically.