169 lines
5.2 KiB
Plaintext
169 lines
5.2 KiB
Plaintext
config CPU_FREQ
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bool "CPU Frequency scaling"
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help
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CPU Frequency scaling allows you to change the clock speed of
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CPUs on the fly. This is a nice method to save power, because
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the lower the CPU clock speed, the less power the CPU consumes.
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Note that this driver doesn't automatically change the CPU
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clock speed, you need to either enable a dynamic cpufreq governor
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(see below) after boot, or use a userspace tool.
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To compile this driver as a module, choose M here: the
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module will be called cpufreq.
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For details, take a look at <file:Documentation/cpu-freq>.
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If in doubt, say N.
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if CPU_FREQ
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config CPU_FREQ_TABLE
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tristate
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config CPU_FREQ_DEBUG
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bool "Enable CPUfreq debugging"
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help
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Say Y here to enable CPUfreq subsystem (including drivers)
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debugging. You will need to activate it via the kernel
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command line by passing
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cpufreq.debug=<value>
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To get <value>, add
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1 to activate CPUfreq core debugging,
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2 to activate CPUfreq drivers debugging, and
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4 to activate CPUfreq governor debugging
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config CPU_FREQ_STAT
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tristate "CPU frequency translation statistics"
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select CPU_FREQ_TABLE
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default y
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help
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This driver exports CPU frequency statistics information through sysfs
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file system.
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To compile this driver as a module, choose M here: the
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module will be called cpufreq_stats.
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If in doubt, say N.
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config CPU_FREQ_STAT_DETAILS
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bool "CPU frequency translation statistics details"
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depends on CPU_FREQ_STAT
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help
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This will show detail CPU frequency translation table in sysfs file
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system.
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If in doubt, say N.
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# Note that it is not currently possible to set the other governors (such as ondemand)
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# as the default, since if they fail to initialise, cpufreq will be
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# left in an undefined state.
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choice
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prompt "Default CPUFreq governor"
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default CPU_FREQ_DEFAULT_GOV_USERSPACE if CPU_FREQ_SA1100 || CPU_FREQ_SA1110
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default CPU_FREQ_DEFAULT_GOV_PERFORMANCE
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help
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This option sets which CPUFreq governor shall be loaded at
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startup. If in doubt, select 'performance'.
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config CPU_FREQ_DEFAULT_GOV_PERFORMANCE
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bool "performance"
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select CPU_FREQ_GOV_PERFORMANCE
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help
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Use the CPUFreq governor 'performance' as default. This sets
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the frequency statically to the highest frequency supported by
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the CPU.
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config CPU_FREQ_DEFAULT_GOV_USERSPACE
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bool "userspace"
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select CPU_FREQ_GOV_USERSPACE
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help
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Use the CPUFreq governor 'userspace' as default. This allows
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you to set the CPU frequency manually or when an userspace
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program shall be able to set the CPU dynamically without having
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to enable the userspace governor manually.
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endchoice
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config CPU_FREQ_GOV_PERFORMANCE
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tristate "'performance' governor"
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help
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This cpufreq governor sets the frequency statically to the
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highest available CPU frequency.
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To compile this driver as a module, choose M here: the
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module will be called cpufreq_performance.
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If in doubt, say Y.
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config CPU_FREQ_GOV_POWERSAVE
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tristate "'powersave' governor"
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help
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This cpufreq governor sets the frequency statically to the
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lowest available CPU frequency.
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To compile this driver as a module, choose M here: the
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module will be called cpufreq_powersave.
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If in doubt, say Y.
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config CPU_FREQ_GOV_USERSPACE
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tristate "'userspace' governor for userspace frequency scaling"
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help
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Enable this cpufreq governor when you either want to set the
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CPU frequency manually or when an userspace program shall
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be able to set the CPU dynamically, like on LART
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<http://www.lartmaker.nl/>.
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To compile this driver as a module, choose M here: the
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module will be called cpufreq_userspace.
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For details, take a look at <file:Documentation/cpu-freq/>.
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If in doubt, say Y.
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config CPU_FREQ_GOV_ONDEMAND
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tristate "'ondemand' cpufreq policy governor"
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select CPU_FREQ_TABLE
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help
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'ondemand' - This driver adds a dynamic cpufreq policy governor.
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The governor does a periodic polling and
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changes frequency based on the CPU utilization.
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The support for this governor depends on CPU capability to
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do fast frequency switching (i.e, very low latency frequency
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transitions).
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To compile this driver as a module, choose M here: the
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module will be called cpufreq_ondemand.
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For details, take a look at linux/Documentation/cpu-freq.
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If in doubt, say N.
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config CPU_FREQ_GOV_CONSERVATIVE
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tristate "'conservative' cpufreq governor"
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depends on CPU_FREQ
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help
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'conservative' - this driver is rather similar to the 'ondemand'
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governor both in its source code and its purpose, the difference is
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its optimisation for better suitability in a battery powered
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environment. The frequency is gracefully increased and decreased
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rather than jumping to 100% when speed is required.
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If you have a desktop machine then you should really be considering
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the 'ondemand' governor instead, however if you are using a laptop,
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PDA or even an AMD64 based computer (due to the unacceptable
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step-by-step latency issues between the minimum and maximum frequency
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transitions in the CPU) you will probably want to use this governor.
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To compile this driver as a module, choose M here: the
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module will be called cpufreq_conservative.
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For details, take a look at linux/Documentation/cpu-freq.
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If in doubt, say N.
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endif # CPU_FREQ
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