Re: How many pentium-3 processors does SMP support?
Tue, 10 Jul 2001 08:26:09 -0700
Chris Wedgwood wrote:
> On Tue, Jul 10, 2001 at 04:19:43PM +0200, Christoph Hellwig wrote:
> The number of CPUs is currently globally limited to 32 by NR_CPUS in
> Ah, so it is... yes, making this architecture dependant might be a
> good idea. Large PPC and MIPS boxen need to adjust this already. Also,
> someone did a starfire port, I think that had 64 processors, not sure.
> You can. But you cannot buy 32-processor PII (-Xeon) systems that are
> supported by Linux.
> What is the limit here? The 8/16 way SE chipsets?
> > In anyone from Compaq is reading this, you should send me a 32-way
> > Xeon ASAP just to prove they really work :)
> It doesn't.
> Oh, then they definately need to send me one.
> Are these not MP1.4 based? Something different?
The Linus-kernel only supports a maximum of 15 Pentium IIIs
due to APIC addressing (4 bits, with 0xf meaning "broadcast").
Pentium 4 uses 0xff for broadcast, so lots more of them can
be supported (when you can find a P-4 MP server).
I have heard of some IBM/Sequent patches that modify the
logical vs. physical APIC addressing scheme to make 16-way
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