Yes, there are clearly architectures where 8 threads share a L2$. L1$ too in both recent POWER SMT8 cores and SPARC Niagras. Yes, Intel Atoms were one of the

Yes, there are clearly architectures where 8 threads share a L2$. L1$ too in both recent POWER SMT8 cores and SPARC Niagras. Yes, Intel Atoms were one of the examples I was thinking of regarding 4 cores sharing an L2$. One can quibble about what counts as a "core" when you're talking about POWER9 or Bulldozers but even being generous I don't think there's ever been a design where 8 cores all share the same L2$.