Re: Lost Ticks on x86_64

Andi Kleen
2005-08-08T16:51:16Z

On Mon, Aug 08, 2005 at 09:47:54AM -0700, Tim Hockin wrote:
> On Mon, Aug 08, 2005 at 02:01:25PM +0200, Andi Kleen wrote:
> > > Some BIOSes do not lock SMM, and you *could* turn it off at the chipset
> > > level.
> >
> > Doing so would be wasteful though. Both AMD and Intel CPUs need SMM code
> > for the deeper C* sleep states.
>
> Really? I'm not too familiar with the deeper C states - what role does
> SMM play?

It does all the hard work of powering down and up the CPU in C2 and C3. On
AMD K8 even C1 (=HLT) executes SMM code depending on the BIOS setup.

-Andi