cpu frequency 资料

[XingChao Wang]

一直对policy/governor的关系有点儿模糊   

重看doc,下图:

Basically, it's the following flow graph:

CPU can be set to switch independently |   CPU can only be set

      within specific "limits" |       to specific frequencies

                                 "CPUfreq policy"

consists of frequency limits (policy->{min,max})

       and CPUfreq governor to be used

/      \

/       \

      /       the cpufreq governor decides

     /       (dynamically or statically)

    /       what target_freq to set within

   /       the limits of policy->{min,max}

  /            \

 /     \

Using the ->setpolicy call, Using the ->target call,

   the limits and the  the frequency closest

    "policy" is set.  to target_freq is set.

 It is assured that it

 is within policy->{min,max}

1. policy是per-cpu

thanks
--wang xingchao