Solaris Turnstiles — RDMSR

An examination of Solaris' turnstile mechanism, a data structure used to implement priority inheritance for blocking mutexes in kernels. It explains why blocking mutexes need compact bookkeeping and how priority inversion arises, then details how turnstiles solve multi-hop priority inheritance by letting threads donate per-thread turnstile structures to contended locks, located via a hash table keyed on lock address. It also covers limitations around multi-owner locks like reader-writer locks, and traces turnstile-like designs into other UNIX-derived kernels, hobby OSes, and userspace constructs such as WebKit's ParkingLot.

Source: https://rdmsr.github.io/writing/turnstiles. 8 Sync News only summarizes and links out; content copyright belongs to the authors and original sources.