Alan Cox <alan@lxorguk.ukuu.org.uk> writes:
> > If you number each CPU so its two IDs are smp_num_cpus()/2
> > apart, you will NOT need to put some crappy hack in the
> > scheduler to pack your CPUs correctly.
>
> Which is a major change to the x86 tree and an invasive one. Right now the
> X86 is doing a 1:1 mapping, and I can offer Marcelo no proof that somewhere
> buried in the x86 arch code there isnt something that assumes this or mixes
> a logical and physical cpu id wrongly in error.
Actually we don't do a 1:1 physical to logical mapping. I currently
have a board that has physical id's of: 0:6 and logical id's of 0:1
with no changes to the current x86 code.
>
> At best you are exploiting an obscure quirk of the current scheduler that is
> quite likely to break the moment someone factors power management into the
> idling equation (turning cpus off and on is more expensive so if you idle
> a cpu you want to keep it the idle one for PM). Congratulations on your
> zen like mastery of the scheduler algorithm. Now tell me it wont change in
> that property.
The idea of a cpu priority for filling sounds like a nice one. Even
if we don't use the cpu id bits for it.
Eric
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This archive was generated by hypermail 2b29 : Sat Dec 15 2001 - 21:00:19 EST