Linsched is a user-space simulator intended to run the Linux scheduling subsystem; it is intended to help developers working on improving (or understanding) the scheduler. A new version, based on 2.6.35, has been released. "Since Linsched allows arbitrary hardware topologies to be modeled, it enables testing of scheduler changes on hardware that may not be easily accessible to the developer. For example, most developers don't have access to a quad-core quad-socket box, but they can use LinSched to see how their changes affect the scheduler on such boxes." Google (the source of this release, but not the original developer) uses Linsched to validate its scheduler work.