On 02/06/2011 14:23, Ivan Voras wrote:
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
Hi,
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.?
The reason why I'm asking is this:
http://msdn.microsoft.com/en-us/library/dd405503%28v=vs.85%29.aspx
It's not necessarily a good approach, but it does have the benefit of
keeping the CPU mask operations atomic... (I don't know if the benefits
of this are big enough).
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