[TriLUG] Questions about Threading

[Mike Johnson]

Jeremy P [jeremyp at pobox.com] wrote:
 
> I think the limitation is more related to motherboard availability for
> Intel processors, rather than than the Linux kernel.

Ding!  That's the real issue.  I think the largest number of Intel
CPUs one can fit on a commercially available (albeit expensive) is
16.
 
> I Googled a bit and can't find the upper limit for the 2.4 kernels, but
> the 2.0 kernels supported up to 16 processors.  I find it very unlikely
> that that number has gone down for newer kernels.

For some reason 64 sticks in my mind, but I think that's wrong.  Check
out <linux/threads.h>.  On my 2.4.10 (yes, I know), I see:
#ifdef CONFIG_SMP
#define NR_CPUS 32              /* Max processors that can be running in SMP */
#else
#define NR_CPUS 1
#endif

So, it looks like the max is 32.

Mike
-- 
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   -- Zorak on Space Ghost

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