More than 32 CPUs under 8.4-P

[Joshua Isom]

On 5/19/2013 10:51 AM, Dennis Glatting wrote:
> On Sun, 2013-05-19 at 11:48 +0200, Tijl Coosemans wrote:
>> On 2013-05-18 19:13, Dennis Glatting wrote:
>>> I have a 4x16=64 core server running FreeBSD 8.4-P but only two of the
>>> CPUs (2x16=32) are enabled. Enabling the other 32 isn't as simple as
>>> changing MAXCPU in param.h (apparently) and recompiling.
>>>
>>> What do I need to do to enable the other 32 cores?
>>
>> Try FreeBSD 9.x. MAXCPU is 64 there.
>>
>
> Not an option.
>
> ZFS hangs on multi-socket systems (Tyan, Supermicro) under 9.1. ZFS does
> not hang under 8.4. This (and one other 4 socket) is a production
> system.
>
>

Does this seem to describe the problem?

http://www.freebsd.org/cgi/query-pr.cgi?pr=177536

You can try switching to 9-stable.  Looking at the source for 8.4, it's 
not being fixed in the 8 series.