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b9170836d1
A new cpufreq module, based on the ondemand one with my additional patches just posted. This one is more suitable for battery environments where its probably more appealing to have the cpu freq gracefully increase and decrease rather than flip between the min and max freq's. N.B. Bruno Ducrot pointed out that the amd64's "do have unacceptable latency between min and max freq transition, due to the step-by-step requirements (200MHz IIRC)"; so AMD64 users would probably benefit from this too. Signed-off-by: Alexander Clouter <alex-kernel@digriz.org.uk> Signed-off-by: Dave Jones <davej@redhat.com>
142 lines
4.6 KiB
Text
142 lines
4.6 KiB
Text
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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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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def_tristate m
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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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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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# 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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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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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.lart.tudelft.nl/>
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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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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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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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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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