The programs that see the most benefit of WO vs TSO are poorly written multithreaded programs. Most of the software you actually use might be higher quality than that?

> TSO must have some value in some contexts, it wasn’t chosen arbitrarily.

Ehhh. I think they might have just backed themselves into it? I believe Intel initially claimed SeqCst but the chips never implemented that and the lack was observable. TSO happened to accurately describe the existing behavior of early multicore Intel chips and they can't exactly relax it now without breaking existing binaries.

Google's AI slop claims Intel published something vague in 2007, and researchers at Cambridge came up with the TSO name and observation in 2009 ("A Better x86 Memory Model: x86-TSO").

https://www.cl.cam.ac.uk/~pes20/weakmemory/x86tso-paper.tpho...

Intel initially claimed Processor Ordering that, IIRC, allows processors doing independent reads of independent writes (IRIW) to observe different orderings. This is slightly weaker than TSO.

In practice Intel never took advantage of this and, given the guarantees provided by the memory barriers, it was hard to formally recover SC, so Intel slightly strengthened it to TSO, which is what was actually implemented in hardware anyway.

I don't think intel ever claimed SC since their first CPU with builtin support for cache coherency (it was the PPro I think?), and the memory model was not well defined before that and left to external chips.