Large machine test ideas

[Sean Bruno]

On Tue, 2011-08-30 at 17:11 -0700, Ivan Voras wrote:
> On 29.8.2011. 20:15, John Baldwin wrote:
> 
> > However, the SRAT code just ignores the table when it encounters an issue like
> > this, it doesn't hang.  Something else later in the boot must have hung.
> 
> Anyway... that machine can in its maximal configuration be populated 
> with eight 10-core CPUs, i.e. 80 physical / 160 logical, so here's a 
> vote from me to bump the shiny new cpuset infrastructure maximum CPU 
> count to 256 before 9.0.
> 
> http://www.supermicro.com/products/system/5U/5086/SYS-5086B-TRF.cfm

Doesn't that (MAXCPU) seriously impact VM usage, lock contention
etc ... ?

I mean, if we have 2 cpus in a machine, but MAXCPU is set to 256, there
is a bunch of "lost" memory and higher levels of lock contention?

I thought that attilio was taking a stab at enhancing this, but at the
current time anything more than a value of 64 for MAXCPU is kind of a
"caveat emptor" area of FreeBSD.

Sean

P.S.  I say 64 as yahoo has been running 64 cpus with local patches for
a while, so I know that this works fairly well.