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by monocasa 2484 days ago
Are their L3 slices MOESI like their L2's are (or at least were). That'd let you have multiple copies in different slices as long as you weren't mutating them.
1 comments

AMD is using MDOEFSI, according to page 15 of: https://www.hotchips.org/wp-content/uploads/hc_archives/hc29...

However, I can't find any information on what MDOEFSI is. I'm assuming:

* Modified * Dirty * Owned * Exclusive * Forwarding * Shared * Invalid

Any information I look up comes up to an NDA-firewall pretty quickly (be it in performance counters, or hardware level documentation). It seems like AMD is highly protective of their coherency algorithm.

> That'd let you have multiple copies in different slices as long as you weren't mutating them.

Seems like the D(irty) state allows multiple copies to be mutated actually. But its still a "multiple copies" methodology. As any particular core comes up to the 8MB (Zen) or 16 MB (Zen2) limit, that's all they get. No way to have a singular dataset with 32MB of cache on Zen or Zen2.