CPUFreqModuleLoading

[oneleaf]

cpufreq (Processor frequency scaling)

Slowing down the CPU can save vast amounts of battery and heat output when the extra (wasted) CPU cycles are not needed. powernowd is reckoned to be better than cpudynd and is the userspace component that monitors the current usage and updates the scaling to reflect need. It talks to the new Linux 2.6 /sysfs cpufreq interface.

Mostly this interface is provided by already loaded ACPI or pmac support. However, some times we need to figure out which extra modules to load; for instance, on PIII-M machines with Intel ICH chipsets, load speedstep-ich.o .

There's the starts of a shell script which greps /proc/cpuinfo and tries to figure out what extra needs loading:

*

[WWW] http://www.paul.sladen.org/ubuntu/cpufreq-detect.sh

The failure-mode isn't too critical; if the module doesn't load, then powernowd doesn't work. Nothing lost, except battery power. This isn't ideal but does mean that nothing is left screwed.

ACPI will also work in most cases, although apparently it may offer less options (eg. only minimum or maximum with nothing in between).
TODO

*

Check if ACPI / pmac has already given us enough
*

Check what needs to doing on PPC PowerBooks
o

Turns out that the cpufrequency module is built in to the kernel on PowerPC, so we don't need to worry about this. AMD64 is currently all powerfreq-k8.ko - the powernowd init script already handles both of these cases. ThomMay
*

figure out relationship with speedstep_lib.o


https://wiki.ubuntu.com/CPUFreqModuleLoading

[leal]

cpufreq (处理器频率调整)

当不需要额外（或不想浪费）CPU周期时，降低CPU频率能够节省大量电池能量，减少热量输出。 powernowd被认为比cpudynd更好，它是用户空间部件，用来监测当前使用情况，并更新调整比例（scaling）反映出需要。powernowd调用了新的Linux 2.6 /sysfs cpufreq接口。

大部分情况下ACPI或pmac支持已经提供了这个接口。不过，有些时候我们需找出要加载哪个特定模块；比如在带有Intel ICH芯片组的PIII-M机器上，需要加载speedstep-ich.o。

下面有个shell脚本，它会查找/proc/cpuinfo并尽力找出需要加载什么特定模块：

*[WWW]http://www.paul.sladen.org/ubuntu/cpufreq-detect.sh

失败的话也不是太严重；如果该模块不能加载，powernowd就是不起作用而已。除了点电池能量也不会损失什么。这么处理虽然不够理想，至少不会留下个烂摊子。

ACPI也能在大部分情况下工作，尽管它能提供的选项较少（比如只有最小值或最大值，而中间没有其它可选值）。

TODO

*检查ACPI/pmac是否已给我们提供足够功能

*检查PPC PowerBooks上需要做些什么
o结果显示在PowerPC上cpufrequency模块已内建于内核中，因此我们不需再为此烦心。目前AMD64都支持powerfreq-k8.ko，powernowd初始化脚本会处理这两种情况。ThomMay

*找出和speedstep_lib.o的关系

https://wiki.ubuntu.com/CPUFreqModuleLoading
_________________

[leal]

翻译完毕。

有些句子怪怪的……

[oneleaf]

http://www.ubuntu.org.cn/support/docume ... howto_view

[millenniumdark]

过时了。

[cnhtcdev]

过时了。

不过时吧。android手机都有Cpu Freq呢