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SubjectRe: [PATCH] x86_64: make amd quad core 8 socket system not be clustered_box v2
On Tue, Feb 26, 2008 at 03:16:16PM -0800, Yinghai Lu wrote:
>On Tue, Feb 26, 2008 at 1:24 PM, Ravikiran Thirumalai <kiran@scalemp.com> wrote:
>>
>> On Tue, Feb 26, 2008 at 01:10:57PM -0800, Yinghai Lu wrote:
>> >On Tue, Feb 26, 2008 at 12:32 PM, Ravikiran Thirumalai
>> ><kiran@scalemp.com> wrote:
>> >> On Tue, Feb 26, 2008 at 11:00:58AM -0800, Yinghai Lu wrote:
>> >> >
>> >> >1. if acpi=off ?
>> >>
>> >> Well that is not a realistic scenario for any multi chassi NUMA machine,
>> >> since the proximity information is very important and turning acpi off
>> >> deprives the OS of this information.
>> >
>> >actually OS should detect the distance instead of rely on SLIT.
>>
>> How does it do that? ACPI SRAT is needed to determine this, and it wouldn't
>> work if acpi=off.
>
>srat only have apicid to node mapping, and ram to node mapping.

Which is very important for performance.

>
>for amd64 system, when acpi=off
>ram to node mapping can be retrieved from pci conf space

I was referring to all types of numa systems, not just AMD. The pci config
space is amd specific. Multi chassi systems in particular would be
acpi SRAT based. Anyways.

Kiran


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