Lockmeter: Highly Informative Instrumentation for Spin Locks in the Linux Kernel

Lockmeter is a tool for instrumenting the spin locks in a multiprocessor Linux kernel. Lockmeter was designed to make minimal cache disruptions, taking care to both minimize cache misses and also to minimize interprocessor cache coherency operations. Lockmeter is "highly informative" in the sense that not only does it record overall statistics for each spin lock, it also reports (where possible) these statistics on a per caller basis. This allows one to readily identify which portions of the kernel code are responsible for causing lock contention. In this paper, we describe the capabilities and implementation of Lockmeter version 1.3.