FreeBSD 7.0-RELEASE: Can I specify the maximum number of cores that ?kernel can recognize ?

[Oliver Fromme]

Hattori, Shigehiro wrote:
 > I try to measure Bind caching name server's multi threading performance on
 > FreeBSD 7 , like below.
 > [...]
 > My testing machine has 8 cores. ( quad core * 2 )
 > 
 > I'd like to specify the maximum # of cores that kernel can recognize.
 > Can I specify the maximum # of cores with boot parameters or something ?

You can reduce the MAXCPUS constant.  The default is 16 on
i386 and amd64.  Unfortunately you have to modify a header
file and recompile your kernel.  The MAXCPUS constant can
be found in /sys/$ARCH/include/param.h and is installed as
/usr/include/machine/param.h.

After reboot you can verify the new value with sysctl
kern.smp.maxcpus (it's a read-only value).

Best regards
   Oliver

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