- Aug 19, 2007
when the fat lady sings.
It's basically a matter of time (Zen 4 surely should have 4-way imho) and a question whether they do SMT4 or general 4-way MT.
Let me rephrase; SMT4 in Zen 3 is not happening. We may/probably will see it at some point though.SMT4 isn't dead, also there might be a CPU ACE unit to decouple OS threads from HW threads.
New patents coming up show cores executing more than 4-threads. (Four threads in execution, and many more in a micro-context buffer. In which, the L3 cache contains even more context info)
The SMT4 mode in Milan(256 macro-context unit)/Vermeer(64 macro-context unit) might need a new operating system. However, its SMT2 mode is backwards compatible. It might also have been delayed like NGG, ¯\_(ツ)_/¯.
Not 100% sure, but "full/heavyweight" context switches retain their security but can now occur in nanoseconds rather than in microseconds.