RE: [RFC] 4-level page table directories.

Luck, Tony
2005-11-10T00:27:48Z

>Is it possible you are mixing up MAX_NUMALINK_NODES (the maximum
>system size, i.e., the maximum number of nodes in a numalink domain)
>with CONFIG_NR_CPUS (the maximum SSI size)?
>
>I'm pretty confident SGI has not proposed setting CONFIG_NR_CPUS\x16384
>to any OSV. ;-)

It's always possible that I'm confused. Here's the message where
Robin introduced the rationale for 4-level page tables:

http://tinyurl.com/bewsk

In that he says "current = 2048" ... which I think is how many
cpus can be in the whole box ... 512 is the current max cpus in
a coherence domain (and thus the max that a single instance of
Linux will see today).

With Montecito (dual core, two threads in each core) the number
of cpus Linux sees will be quadrupled in a system with the same
number of sockets. Add more sockets, and the 16384 number may
not be impossible.

-Tony