Efficient, Distributed, and Non-Speculative Multi-Address Atomic Operations
Eduardo José Gómez-Hernández, Juan M. Cebrián, Rubén Titos-Gil, Stefanos Kaxiras, Alberto Ros · 2021
Critical sections that read, modify, and write (RMW) a small set of addresses are common in parallel applications and concurrent data structures. However, to escape from the intricacies of fine-grained locks, which require reasoning about all possible thread interleavings, programmers often resort to coarse-grained locks to ensure atomicity. This results in atomic protection of a much larger set of potentially conflicting addresses, and, consequently, increased lock contention and unneeded serialization. As many before us have observed, these problems would be solved if only general RMW multi-address atomic operations were available, but current proposals are impractical because of deadlock scenarios that appear due to resource limitations. Alternatively, transactional memory can detect conflicts at run-time aiming to maximize concurrency, but it has significant overheads in highly-contended critical sections.