--Andi Kleen <ak@xxxxxxx> wrote (on Saturday, February 07, 2004 04:54:03 +0100):
"Martin J. Bligh" <mbligh@xxxxxxxxxxx> writes:
If we really want to do good testing, we should make a fake NUMA configI have such a patch for x86-64 if anybody is interested in that.
that can run a 4x SMP box as fake NUMA, with half the memory in each
"node" and half the processors ... but I never got around to coding that ;-)
x86-64 low level NUMA is quite different from IA32 NUMA though so it would be a bit difficult to port.
Not quite sure what you mean ... I was driving at pretending an SMP box
was NUMA ... but the x86_64 is already NUMA ... are you grouping nodes
together into single nodes with 2 cpus each?
What might be intriguing is to use Nick's domains stuff to create a heirarchy
for the scheduler where we have 1 cpu nodes and 2 cpu nodes above that, but
still keep the normal NUMA stuff flat for mem allocation. What might be interesting is a heirarchy where if this is the HT connections of cpu layouts:
1 --- 2
| |
| | | |
3 --- 4
then domains of (1,2,3) (2,3,4) (1,3,4) (1 2 4), with a view to restricting
the "double hop" traffic as much as possible. But I'm not sure the domains
code copes with multiple overlapping domains - Nick?