torellip@arena.sci.univr.it (Technolord) writes:
> Usually, no. That is, "slowdown" modes usually come in after some time the
> system is unused by the USER. In other words, it counts the time you don't
> move the mouse, touch the keyboard, not how much CPU is idle. I say
> usually, for at least one (crusoe) chip does measure the cpu consumption
> and act consequently. I don't know others. On i386 (and many other
> achitectures) if the cpu is idle, it's actually running an "idle loop"
> anyway (or, if the OS wants, do something like flush caches, zero unused
> memory, so on).

Are you talking about some MS product or BSD?
If you look at locore.s is certainly looks like netbsd does a halt
instruction to power down.


    idle:     call context_switch
              halt
              jump idle

The important thing about the halt instruction is that it will put
large parts of the CPU and system into a low-power state.  Taking this
out doubles the power usage on a Vaio 505tx.

I'm beginning to wonder if it wouldn't be possible to lower the
power-consumption of netbsd even further by cutting down on the
clock-interrupts.  Having the CPU interrupted and power-ed up 100
times per second has got to take its toll.  Has anyone played with
tuning the kernel for even more power savings?

-wolfgang
-- 
       Wolfgang Rupprecht <wolfgang+gnus@dailyplanet.wsrcc.com>
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