Re: [PATCH V6 0/7] ACPI: Support Generic Initiator proximity domains

On Fri, 3 Jan 2020 13:18:59 +0100
Brice Goglin [off-list ref] wrote:

Le 03/01/2020 à 11:09, Jonathan Cameron a écrit :

quoted

1) If the memory and processor are in the same domain, that should mean the
access characteristics within that domain are the best in the system.
It is possible to have a setup with very low latency access
from a particular processor but also low bandwidth.  Another domain may have
high bandwidth but long latency.   Such systems may occur, but they are probably
going to not be for 'normal memory the OS can just use'.

2) If we have a relevant "Memory Proximity Domain Attributes Structure"
Note this was renamed in acpi 6.3 from "Address Range Structure" as
it no longer has any address ranges.
(which are entirely optional btw) that indicates that the memory controller
for a given memory lies in the proximity domain of the Initiator specified.
If that happens we ignore cases where hmat says somewhere else is nearer
via bandwidth and latency.

For case 1) I'm not sure we actually enforce it.
I think you've hit case 2).  

Removing the address range structures should work, or as you say you can
move that memory into separate memory nodes.  

I removed the "processor proximity domain valid" flag from the address
range structure of node2, and the GI is now its access0 initiator
instead of node2 itself. Looks like it confirms I was in case 2)

Thanks

Brice

Cool. I was wondering if that change would work fine.
It is a somewhat crazy setup so I didn't have an equivalent in my test set.

Sounds like all is working as expected.

Thanks,

Jonathan


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