Locks

Use locks to allocate and free internal operating system memory.

For more information, see Understanding Locking.

Types of locks
The Open Software Foundation/1 (OSF/1) 1.1 locking methodology was used as a model for the AIX® multiprocessor lock functions.
Lock granularity
A programmer working in a multiprocessor environment must decide how many separate locks must be created for shared data. If there is a single lock to serialize the entire set of shared data items, lock contention is comparatively likely. The existence of widely used locks places an upper limit on the throughput of the system.
Locking overhead
Requesting locks, waiting for locks, and releasing locks add processing overhead.
Waiting for locks
When a thread wants a lock already owned by another thread, the thread is blocked and must wait until the lock becomes free.

Parent topic: Symmetrical Multiprocessor concepts and architecture