Re: [Bug fix PATCH 1/2] acpi, movablemem_map: Exclude memblock.reserved ranges when parsing SRAT.

[Tang Chen <tangchen@cn.fujitsu.com>]

On 02/25/2013 09:35 AM, Will Huck wrote:
> On 02/21/2013 06:41 AM, Luck, Tony wrote:
>>> What's the relationship between e820 map and SRAT?
>> The e820 map (or EFI memory map on some recent systems) provides
>> a list of memory ranges together with usage information (e.g. reserved
>> for BIOS, or available) and attributes (WB cacheable, uncacheable).
>>
>> The SRAT table provides topology information for address ranges. It
>> tells the OS which memory is close to each cpu, and which is more
>> distant. If there are multiple degrees of "distant" then the SLIT table
>> provides a matrix of relative latencies between nodes.
>
> What's the meaning of multiple degrees of "distant" here? Eg, there are
> ten nodes, can SRAT tell each node which memory on other node is more
> close or distant? If the answer is yes, why need SLIT since processes
> can use memory close to their nodes.

Hi Will

Referring to the ACPI spec, SRAT provides info of each node, and SLIT
provides info between nodes and nodes, I think.

SRAT provides number of CPUs and memory of node i, memory range, the PXM 
id which
will be mapped to node id, and hotplug info, and so on.

SLIT provides a matrix describing the distances between node i and node j.

>
>
> SRAT and SLIT are get from firmware or UEFI?
>
I think we can get this info from ACPI BIOS.

Thanks. :)

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