Re: cpuidle asymmetry (was Re: [RFC PATCH V4 5/5] cpuidle: cpuidledriver for apm)

[Arjan van de Ven]

On 4/1/2011 1:15 AM, Dipankar Sarma wrote:
> On Fri, Apr 01, 2011 at 12:09:25AM -0400, Len Brown wrote:
> > > > Moorestown is already an example of an asymmetric system,
> > > > since its deepest c-state is available on cpu0, but not on cpu1.
> > > > So it needs different tables for each cpu.
> > > wtf are these hardware guys smoking and how the heck are we supposed to
> > > schedule on such a machine? Prefer to keep cpu1 busy while idling cpu0?
> > they are smoking micro-amps:-)
> >
> > S0i3 on cpu0 can be entered only after cpu1 is already off-line,
> > among other system hardware dependencies...
> >
> > So it makes no sense to export S0i3 as a c-state on cpu1.
> >
> > When cpu1 is online, the scheduler treats it as a normal SMP.
> Isn't S0i3 a "system" state, as opposed to cpu state ?

it's misnamed. it's a C state to the OS.


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