Messages in this thread | | | Date | Wed, 12 Dec 2001 10:25:17 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: Near CPUs ... |
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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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