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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