get_cyclecount(9) deprecation

[Kostik Belousov]

On Fri, Mar 18, 2011 at 05:51:27PM +0200, Andriy Gapon wrote:
> on 18/03/2011 15:56 Kostik Belousov said the following:
> > On Fri, Mar 18, 2011 at 05:26:53PM +1100, Bruce Evans wrote:
> > ...
> >> - set cputicker() has some design bugs.  It assumes that the tick frequency
> >>   is the same across all CPUs, but the TSC is per-CPU.  I have an old SMP
> >>   system with CPUs of different frequency that can demonstrate bugs from
> >>   this.
> > We definitely do not support configurations with different models of
> > CPUs in SMP, this is what Simmetric is about. Different as in frequency
> > or stepping.
> 
> Are there any fundamental reasons for us to not support that configuration in
> situations where hardware and BIOS (in x86 case) happen to support it?
> 
> I am personally more interested in non-uniform topologies like one package having
> two cores and another having four.

We do not handle CPU errata/quirks individually per-core. I think that we
assume that all cores have the same stepping and thus require the same
workarounds, if any, as BSP. Also, I think tsc calibration is done
only on BSP, but I may be wrong there.
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