Linux Futexes: Spinlocks vs. Futexes – A Performance Deep Dive

This article delves into the implementation and performance of futex locks in Linux. The author first implements a simple spinlock, then builds a more sophisticated mutex using the futex syscall. Experiments reveal that simple spinlocks can outperform futexes in certain scenarios, especially when critical section operations are lightweight. However, when critical sections are time-consuming and thread contention is high, futexes offer a significant advantage by avoiding unnecessary CPU spinning. The article concludes by discussing methods to improve futex lock performance and emphasizes the need to choose the right locking mechanism based on the specific application context.