Re: Near CPUs ...

From: Davide Libenzi (
Date: Wed Dec 12 2001 - 13:25:17 EST

On Wed, 12 Dec 2001, Martin J. Bligh wrote:

> > 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 :
> IIRC, for HT, cpus with an APICid that only differ in the last bit are paired
> (ie (0,1), (2,3), (3,4) ....)
> For systems with clustered APIC ID, the cluster number is the top nibble of the
> logical APICid - CPUs with the same cluster number are in the same node.

This info is good enough for now but i think there should be an abstract
interface inside the kernel to get topology infos.
I looked at SRAT tables, they're good if they'll be a standard w/out M$
patents. Otherwise the ACPI2 _PXM method can be used.

- Davide

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