Interesting, so it behaves more or less like pthread_cond_reltimedwait_np() in Solaris? I wonder which came first.

The context is a UDP network receiver which infers packet loss after a timeout:

https://github.com/facebook/netconsd/blob/main/threads.c#L15... https://github.com/facebook/netconsd/blob/main/worker.c#L526

Time while sleeping doesn't matter here.