Scheduler Activation

Scheduler activations provide additional kernel scheduling support for multithreaded applications. This is implemented as a private interface between the kernel and the libthread library (or libpthread), without changing the libthread (libpthread) interface. Among other things, this enables the thread library to implement adaptive mutex locks. Adaptive mutex locks is where a thread trying to acquire a lock spins if the thread holding the lock is currently running on a processor, and blocks otherwise.

See the libsched(3X) man page for more information.