Re: load and power management

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On Tue, Apr 13, 2010 at 7:51 PM, Peter A <loony@xxxxxxxxxxxx> wrote:

> Am I doing something wrong? My view is pretty simple but the few tests I did
> seemed to all indicate the same thing...
>
> How valuable is reporting the CPU usage if its not really shows how much of
> maximum CPU power is used?

> Wouldn't it make more sense to show CPU usage normalized to the maximum
> frequency rather than the current frequency?
>
> Does the load as display with uptime compensate for power management? I went
> through some of the kernel code the scheduler and the cpufreq kernel modules
> but didn't see anything.

I don't think so.  From my  understanding,  the load is computed by
sampling at a given interval. The per process load is a function of
how often a particular PID shows up in the sample.

http://www.teamquest.com/resources/gunther/display/5/index.htm

I believe this method is used because of limits in a processor knowing
its "speed". I.e., every processor has different metrics, identity
strings, etc.. We can calculate synthetic numbers like bogomips, but
this won't be valid throughout the run of the system (system is not
necessarily at full power during boot or vice versa).  To add to this,
the metrics are computed in the kernel so there are performance and
possibly other technical reasons that calculating those numbers can't
be done.
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