Multi CPU support in 6.0

[Kris Kennaway]

On Mon, Nov 07, 2005 at 05:15:55PM +0100, Achim Patzner wrote:
> 
> Am 07.11.2005 um 16:27 schrieb Ollivier Robert:
> 
> >According to Steven Hartland:
> >>I believe previously smp support in FreeBSD has been limited
> >>to smaller numbers of CPU's, we've got the opportunity to test
> >>an 8 way dual core ( 16 cpu's ) this week, is 6.0 up to this?
> >
> >I recall seeing someone on IRC saying they had a 14 CPU machine  
> >(Sparc64
> >E4500) to play with so I think it should be ok.

That would be me (machine courtesy of hrs@).  He also donated a 12-
and 10- CPU version, all of which I use for package building and SMP
performance testing.  These machines have been invaluable for testing
and improving FreeBSD on SMP, and have caused innumerable bugs to be
found and fixed.

> I remember someone writing that the intermediate state of -CURRENT  
> while removing the giant lock around the kernel wasn't viable with  
> more than four CPUs as it would completely deadlock from time to  
> time. I guess we're a bit further down the road...

That certainly seems to be the case.  You want to use FreeBSD 6.0,
which has excellent performance and stability on SMP in my testing,
even with 14 CPUs.  FreeBSD 5.4 is definitely not up to it, since VFS
is under Giant.

Kris
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