Re: __atomic_test_and_set() and mips o32 - help wanted

[Jason Thorpe <thorpej%me.com@localhost>]

> On Nov 19, 2025, at 1:17 PM, Jason Thorpe <thorpej%me.com@localhost> wrote:
> 
> The traps themselves are cheap, but that does not always equate to “trap handling is cheap”.
> 
> I agree with you vis a vis "making appropriate trade-offs is good, actually”, but I’d also like to point out that work described in the original paper on restartable atomic sequences was done on an R3000 (DECstation 5000/200).

It’s also worth remembering that emulating ll/sc requires **two** traps per “atomic test-and-set”.  Unless, of course, you’re going to increase the complexity of the trap handler to work forward from the ll and interpret the instructions up to the sc.

-- thorpej