[PATCH] Add the infrastructure for supporting an infinite number of CPUs

Ivan Voras ivoras at freebsd.org
Thu Jun 2 12:23:18 UTC 2011

On 01/06/2011 20:21, Attilio Rao wrote:
> Current maximum number of CPUs supported by the FreeBSD kernel is 32.
> That number cames from indirectly by the fact that we have a cpumask_t
> type, representing a mask of CPUs, which is an unsigned int right now.
> I then made a patch that removes the cpumask_t type and uses cpuset_t
> type for characterizing a generic mask of CPUs:
> http://www.freebsd.org/~attilio/largeSMP/largeSMP-patchset-beta-0.diff


I'm just wandering: what is the expected overhead of this, compared to 
using a simple atomic integer (32-bit on i386, 64-bit on amd64)? I 
assume that this will introduce more work, like locking, in 
performance-critical code like the scheduler, etc.?

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