STI, HLT in acpi_cpu_idle_c1

John Baldwin jhb at
Tue Jun 22 22:05:08 GMT 2004

On Tuesday 22 June 2004 05:34 pm, Matthew Dillon wrote:
> :On Thursday 17 June 2004 07:33 pm, Matthew Dillon wrote:
> :>     It kinda sounds like ACPI has bokered the other cpus.  I'm not sure
> :>     why one would even *want* to use ACPI to idle down Xeon's in an MP
> :>     system, actually :-)
> :
> :Power and heat savings.
> :
> :--
> :John Baldwin <jhb at>  <><
>     All well and nice, but if you want power and heat savings you don't
>     purchase a big honking SMP box in the first place.
>     This sounds like a disaster waiting to happen to me.  ACPI barely works
>     on UP systems, there is no way I would ever trust it to properly HLT or
>     otherwise screw around with the cpu timing on an SMP system.  HLT is
>     plenty good enough.  IMHO this type of feature is not something that
>     should be turned on by default on SMP.

Certain large CPU vendors disagree.

John Baldwin <jhb at>  <><
"Power Users Use the Power to Serve"  =

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