dirtypersian
Joined 10 years ago
Joined 10 years ago
Relevant: https://en.wikipedia.org/wiki/Founder%27s_syndrome#:~:text=F....
I don't agree with this. What do uops have anything to do with ooo execution. I can easily make a CPU with no uops doing ooo execution. Unless I'm misunderstanding and the article is just saying smaller cores don't do ooo since they are trying to stay within a certain area/power footprint.
Yeah, I think that's key to understanding this. They are supporting a version of ARM ISA running that maintains TSO even though official ARM doesn't need to support TSO. I guess this is all to get better emulation performance and avoid those extra synchronization instructions that would have to be added by Rosetta if the silicon did not have TSO support.
I don't really know much about the internals of macOS but figuring out when there are applications for example running on two different cores (since TSO is only really needed for multi-core use cases) that need to access the same memory and then applying TSO on the fly like that seems difficult. If that is what Rosetta2 is actually doing, that is impressive.