CPU Frequency scaling allows you to change the clock speed of CPUs on the fly. This is a nice method to save power, because the lower the CPU clock speed, the less power the CPU consumes. Note that this driver doesn't automatically change the CPU clock speed, you need to either enable a dynamic cpufreq governor (see below) after boot, or use a userspace tool. For details, take a look at <file:Documentation/cpu-freq>. If in doubt, say N.
This driver exports CPU frequency statistics information through sysfs file system. To compile this driver as a module, choose M here: the module will be called cpufreq_stats. If in doubt, say N.
This will show detail CPU frequency translation table in sysfs file system. If in doubt, say N.
This option sets which CPUFreq governor shall be loaded at startup. If in doubt, select 'performance'.
Use the CPUFreq governor 'performance' as default. This sets the frequency statically to the highest frequency supported by the CPU.
Use the CPUFreq governor 'powersave' as default. This sets the frequency statically to the lowest frequency supported by the CPU.
Use the CPUFreq governor 'userspace' as default. This allows you to set the CPU frequency manually or when a userspace program shall be able to set the CPU dynamically without having to enable the userspace governor manually.
Use the CPUFreq governor 'ondemand' as default. This allows you to get a full dynamic frequency capable system by simply loading your cpufreq low-level hardware driver. Be aware that not all cpufreq drivers support the ondemand governor. If unsure have a look at the help section of the driver. Fallback governor will be the performance governor.
Use the CPUFreq governor 'conservative' as default. This allows you to get a full dynamic frequency capable system by simply loading your cpufreq low-level hardware driver. Be aware that not all cpufreq drivers support the conservative governor. If unsure have a look at the help section of the driver. Fallback governor will be the performance governor.
This cpufreq governor sets the frequency statically to the highest available CPU frequency. To compile this driver as a module, choose M here: the module will be called cpufreq_performance. If in doubt, say Y.
This cpufreq governor sets the frequency statically to the lowest available CPU frequency. To compile this driver as a module, choose M here: the module will be called cpufreq_powersave. If in doubt, say Y.
Enable this cpufreq governor when you either want to set the CPU frequency manually or when a userspace program shall be able to set the CPU dynamically, like on LART <http://www.lartmaker.nl/>. To compile this driver as a module, choose M here: the module will be called cpufreq_userspace. For details, take a look at <file:Documentation/cpu-freq/>. If in doubt, say Y.
'ondemand' - This driver adds a dynamic cpufreq policy governor. The governor does a periodic polling and changes frequency based on the CPU utilization. The support for this governor depends on CPU capability to do fast frequency switching (i.e, very low latency frequency transitions). To compile this driver as a module, choose M here: the module will be called cpufreq_ondemand. For details, take a look at linux/Documentation/cpu-freq. If in doubt, say N.
'conservative' - this driver is rather similar to the 'ondemand' governor both in its source code and its purpose, the difference is its optimisation for better suitability in a battery powered environment. The frequency is gracefully increased and decreased rather than jumping to 100% when speed is required. If you have a desktop machine then you should really be considering the 'ondemand' governor instead, however if you are using a laptop, PDA or even an AMD64 based computer (due to the unacceptable step-by-step latency issues between the minimum and maximum frequency transitions in the CPU) you will probably want to use this governor. To compile this driver as a module, choose M here: the module will be called cpufreq_conservative. For details, take a look at linux/Documentation/cpu-freq. If in doubt, say N.