[simoncion]

> Releasing support for such CPU:s pretty much as soon as they were available rather than a few years later probably says something about the required effort.

I doubt it. You should read the PDF in footnote zero from my previous comment. I'll copy the link here for your convenience. <https://erlang.org/euc/08/euc_smp.pdf>

[cess11]

"The history of support for SMP (Symmetrical Multi Processor) in Erlang started around 1997-1998"

"The SMP work was restarted at 2005"

"The first release of a stable runtime system with support for SMP came in OTP R11B in May 2006."

The Duo launched in July the same year. Pentium D was released in May 2005, as was Athlon 64 X2.

[simoncion]

> The Duo launched in July the same year. Pentium D was released in May 2005, as was Athlon 64 X2.

Multi-socket machines predate these processors by at least ten years. Windows NT 4.0 (first released in 1996) had multiprocessor support, as did Linux 2.0 (also released in 1996).

If you don't want to bother verifying this information, gut-check it. Ask yourself: "Why on earth would the Masters work on adding SMP to Erlang have started in 1997 if there weren't already working computers that could have benefited from SMP? And would it have made any sense to do this work if those sorts of computers hadn't already been around for a while?"