The spinlock is the most basic mutual exclusion primitive provided by a multiprocessor operating system. Spinlocks need to protect against preemption on the current CPU (typically by disabling interrupts, but we’ll ignore that aspect in this post) and also against attempts by other cores to concurrently access the critical section (by using atomic memory operations). As the name implies, attempts to acquire a locked spinlock simply spin: they burn CPU time. Thus, we don’t want to hold spi...
