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Re: NR_CPUS 's value

On Thu, 2004-11-04 at 09:20 +0800, Bao zhao wrote:

>   In kernel, NR_CPU  is macro and represents the number of CPUs. Many arrays 
> use it to define array's size . But the number of CPUs can be known only 
> when smp machine boot, so when compling  the kernel , NR_CPU has no value.
>    I am cofused by it .

NR_CPUS represents the maximum number of processors supported, not the
current number on a live system (that is smp_nr_cpus or something
similar).  The value is known at compile-time.  It is set by
CONFIG_NR_CPUS which is usually 32 if CONFIG_SMP is set.

The macro is just used to size static arrays, although such use is
falling out of favor as we now have support for many processors.

	Robert Love



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