Friday October 21 at 10am, in CIT 368 Waffinity is a project implemented by NetworkAppliance that enables high-performing, highly-concurrent execution of filesystem operations on a 4 processor hardware platform. The most important filesystem operations were rewritten to be "Waffinity-safe" and allowed to run in parallel with other Waffinity-safe operations. The remaining non-Waffinity ops are guaranteed to run exclusively and thus do not need the same level of synchronization. Waffinity has significantly improved WAFL (Write Anywhere File Layout) performance on 4-way machines under a variety of workloads. Side goals of the project included: easy to implement, processor cache and NUMA optimized, fitting in with the existing programming model, and avoiding the overhead of fine-grained synchronization. This talk will explain the motivation for, design of, and implementation of Waffinity.