Optimizing a FIFO, scalable spin lock using consistent memory

This paper presents a FIFO queue-based spin lock that (1) uses only one atomic swap operation; (2) is scalable as it requires a constant amount of communication; (3) runs without a coherent cache support; and (4) provides a timing guarantee required for real-time applications. The algorithm is optimal in terms of the number of atomic operations required to solve a scalable mutual exclusion problem in NUMA architectures, improving on Craig's spin lock 5] that uses four atomic swap operations. It minimizes the number of atomic operations by replacing them with non-atomic read and write operations. This optimization can beneet greatly from modern multiprocessors where non-atomic memory operations are much more optimized than atomic operations. The algorithm runs correctly in various weakly consistent memories, providing a potentially signiicant speed-up over the algorithms with more atomic operations.