Does NUMA help dual-core processors?

[ThomasJ02]

Does anyone know if NUMA (non-uniform memory access) helps dual-core processors? As I understand it, basically NUMA encourages certain processors to access certain areas of memory that are 'closer' to them. But if both procs are on the same chip, does it matter at all?

 

[bersl2]

No. NUMA only helps when processors are not the same logical distance from memory. For instance, NUMA allows one Opteron to access memory attached to the other Opteron's bank. Since the dual cores are both attached to the same memory bank, there is no point to NUMA, and all it does is add overhead.

Though, somebody is always free to correct me if wrong.

 

[Viditor]

Originally posted by: bersl2
No. NUMA only helps when processors are not the same logical distance from memory. For instance, NUMA allows one Opteron to access memory attached to the other Opteron's bank. Since the dual cores are both attached to the same memory bank, there is no point to NUMA, and all it does is add overhead.

Though, somebody is always free to correct me if wrong.

Not really...NUMA allows one GROUP of Opterons to access other groups. Opteron is a special case because not only are all the memory banks of the same motherboard available to each other, but the caches of each processor can also be directly snooped.
This is of course due to the HT links...