[rescue] Best brains: Â Dead keyboard ports on PC hardware

nate at portents.com nate at portents.com
Fri Jun 22 18:03:33 CDT 2007

> I've only seen it supporting more than 2 cores when used with a special
> vendor supplied HAL supplied by the hardware vendor.  One example of
> that is a SGI VW 540, a quad P3 Xeon system.  When I used Win2K on a
> dual processor Xeon with HT, 2K would only see 2 CPUs, while linux and
> XP saw the same machine as a Quad CPU machine.  I guess this was in the
> 2002 timeframe.

That's very unfortunate... here I've been assuming that since the CPU
licensing terminology didn't change from Windows 2000 to XP and since both
were MP-aware kernels and the processor limitations regarding XP were
solely based on the arbitrary licensing restrictions that MS cooked up for
their product and there is no upward bound on the number of supported
cores per physical processor for XP, that 2000 would behave the same.

My guess is that MS changed the behavior with XP as a side-effect of their
"Hyperthreading-aware scheduler" that they introduced with XP, where they
simply made sure to load balance across physical processors in the case of
two Hyperthreaded processors in a system, rather than load up a single
hyperthreaded physical CPU with two high load processes and leave the
other idling.

- Nate

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