Re: Near CPUs ...

[Alan Cox]

> that lists metrics between CPUs, ie :
> 
> metric(I, J) = F(cpus_dmap[I][J])
> 
> and this is the easy part.
> How to detect CPUs that are "near" ( on the same bus/mb ) on x86/ia64 hardware ?
> Is the MP configuration data structured in a way that makes you understand
> this mapping, ie :

The MP 1.1/1.4 mappings have no information on memory or locality. The ACPI
stuff seems to have the same limitations. The ACPI one does correctly
describe hyperthreading pairs (two execution units per die) - but while they
are "closer" they are also less efficient than two seperate cpus for most
tasks.