Editing Symmetric multiprocessing (section)

== Performance ==
When more than one program executes at the same time, an SMP system has considerably better performance than a uniprocessor system, because different programs can run on different CPUs simultaneously. Conversely, [[asymmetric multiprocessing]] (AMP) usually allows only one processor to run a program or task at a time. For example, AMP can be used in assigning specific tasks to CPU based to priority and importance of task completion.  AMP was created well before SMP in terms of handling multiple CPUs, which explains the lack of performance based on the example provided.

In cases where an SMP environment processes many jobs, administrators often experience a loss of hardware efficiency. Software programs have been developed to schedule jobs and other functions of the computer so that the processor utilization reaches its maximum potential. Good software packages can achieve this maximum potential by scheduling each CPU separately, as well as being able to integrate multiple SMP machines and clusters.

Access to RAM is serialized; this and [[cache coherency]] issues cause performance to lag slightly behind the number of additional processors in the system.