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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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