> You probably don't want to have global shared locks and frequent atomic operations on CXL-backed shared memory (once that becomes possible in theory with CXL3.0).

I'd bet contested locks spend more time in cache than most other lines of memory so in practice a global lock might not be too bad.

Yep agreed, for single-host with CXL scenarios. I wrote this comment thinking about a hypothetical future CXL3.x+ scenario with multi-host fabric coherence where one could in theory put locks and control structures that protect shared access to CXL memory pools into the same shared CXL memory (so, no need for coordination over regular network at least).