This article investigates split locks on x86-64 architectures, where atomic operations crossing cache line boundaries trigger slow bus locks that degrade system performance. It examines how modern CPUs trap these operations and Linux implements mitigation through artificial delays. The author conducts practical testing to measure the performance impact of split locks versus normal atomic operations.
Background
Atomic operations are fundamental to multithreaded programming, allowing threads to safely manipulate shared data without traditional locks. Modern x86 CPUs handle these operations at the cache line level through coherency protocols.
- Source
- Lobsters
- Published
- Apr 11, 2026 at 11:32 PM
- Score
- 7.0 / 10