[linux-pm] [PATCH] tracing, perf: add more power related events

Thomas Renninger trenn at suse.de
Mon Sep 6 05:00:05 PDT 2010


On Monday 06 September 2010 13:27:13 Jean Pihet wrote:
> On Mon, Sep 6, 2010 at 12:42 PM, Thomas Renninger <trenn at suse.de> wrote:
...
> In order to reach an efficient low power mode you
> need to ensure that all clocks in a clock domain are idled or cut off
> (automatically by the HW or with the intervention of SW drivers).
> 
> The HW complexity requires the tracing of all those clocks/power
> states, that is why new events are proposed.
Hm, but if the HW can switch clocks behind your back, how do you
realize that to throw a perf clock power event then?
Theoretically you need to poll to keep track of HW switching the
clocks?

    Thomas


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