[dragontamer]

"Pause" spins give all their resources to the hyperthread-sibling. So unless the hyperthread-sibling is also stalled out for some reason, the "pause" instruction is definitely preferred.

So its not like resources are lost (at least, under high CPU utilization). But still, you're right in that a 29ms spin-lock sounds outrageous to me. That's definitely long.

[cma]

Pause can be t he best choice even without hyperthreading because it can lower power utilization. And even on desktop that can mean less heat and more time for other stuff to run at a higher-clocked 'Turbo-boost'.