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SubjectRE: SMP cpu deep sleep
>From: [mailto:linux-kernel-
>] On Behalf Of Hans Kristian Rosbach
>Sent: Friday, August 20, 2004 1:07 AM
>Subject: SMP cpu deep sleep
>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.

Most SMP server systems today don't support the C-states beyond C1 (at
least on x86 or x86-64, as far as I know). If your system supports that,
I think it would be nice to do that.


>It would be a cool feature.
> Hans K. Rosbach

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