Usually it is not. Acq rel only is useful when you can prove ordering of everything else can be nonsequential but still need internal (in-function) ordering gua

Usually it is not. Acq rel only is useful when you can prove ordering of everything else can be nonsequential but still need internal (in-function) ordering guarantees. Generally you really have to run a miniature proof or exhaustive ordering analysis to be sure. It is useful when implementing nonserialized queues. (especially if you keep a Lamport timestamp or equivalent yourself for other reasons) Release write/relaxed read is more useful, typically for work/cancel/finish flags that are spun on similarly to condition variables.