[$] Cache awareness for the CPU scheduler

The kernel's CPU scheduler has to balance a wide range of objectives. Thetasks in the system must be scheduled fairly, with latency for any giventask kept within bounds. All of the CPUs in the system should be kept busyif there is enough work to do, but unneeded CPUs should be shut down toreduce power consumption. A task should also run on the CPU that is mostlikely to have cached the memory that task is using. This patchseries from Chen Yu aims to improve how the scheduler handles cachelocality for multi-threaded processes.