While AMD is still hard at work tweaking and refining its flagship 16 core Ryzen 9 3950X to get it ready for prime time in two months time, the company has reportedly completed the design of its next generation Zen 3 core microarchitecture, and it packs one hell of a surprise.
Rumor: AMD Zen 3 Architecture to Support up to 4 Threads Per Core With SMT4 Feature
Rumor has it, that AMD's next generation CPU microarchitecture is going to have a brand new feature called SMT4, and as the name implies it's a simultaneous multi-threading feature. Whilst the company's Zen 2 core does improve on the SMT capability of the original Zen architecture, which was the company's first ever design to feature SMT, Zen 3 is said to make a giant leap forward by doubling the execution thread count per core from two to four.
AMD won't be the first ever company to do this kind of thing. some iterations of IBM's Power architecture support up to eight execution threads per core. However, if the rumors are to be believed, AMD will be the first ever to introduce a (mainstream) x86 microarchitecture capable of executing more than two threads per core.
As CPU microarchitectures become more complex and as the cores get bigger and bigger some parts of the pipeline grow underutilized and inefficiencies are bound to inherently show up whilst existing ones could grow more exaggerated. This is why SMT makes sense to begin with, and enabling the design to take advantage of these inefficiencies and underutilized resources by executing additional threads per core may be the right solution, if done right and not at the expense of single threaded performance.
If what the rumor alleges ever comes to fruition, SMT4 could be a game changer for the server market. Until then however, take it with a grain of salt.