SMP cpu deep sleep

[Hans Kristian Rosbach]

While reading through hotplug and speedstep patches
I came to think of a feature I think might be useful.

In an SMP system there are several cpus, this generates
extra heat and power consuption even on idle load.
Is there a way to put all cpus but cpu1 into a kind of
deep sleep? Cpu1 would have to do all work (including irqs)
of course.

We have a lot of SMP systems that we host, and they
are heavily used ~10 hours of the day, the rest they are
mostly idle. They could run on only 1 cpu during lenghty
idle periods.

If it is possible to put cpus to a deeper sleep than
just the simple idle, then the kernel could make use of this.

It would be a cool feature.

Sincerly
    Hans K. Rosbach


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