Multiprocessing: Difference between revisions

Multiprocessing involves more than one CPU in a computer. There are a variety of ways that multiprocessing may be implemented in hardware.

 

== SMP (Symmetric Multiprocessing) ==

 

In theory [[SMP]] means that all CPUs are identical. In practice there may be minor variations between CPUs (e.g. different revisions of the same family of CPUs), but these differences can usually be ignored by operating system software. SMP is the easiest form of multiprocessing for software to support. SMP includes systems with CPUs implemented in separate chips, systems with CPUs implemented in the same chip (multi-core) and combinations (e.g. a system with 2 separate quad core chips, with a total of 8 physical CPUs).

 

== SMT (Simultaneous Multithreading) ==

 

For most NUMA 80x86 systems the NUMA ratio is quite low (around 1.2), and an operating system could treat these systems as UMA without severe performance problems.

 

== Topology ==

 

This map may include the contents of each NUMA domain (number of CPUs and their IDs, number of RAM areas and their sizes and locations in the physical address space, number of I/O hubs and their identification, etc), plus performance data (e.g. tables that can be used to determine the relative cost of accessing a specific location in RAM, a specific I/O hub and/or another CPU from any CPU; and/or information about cache sharing between CPUs).

 

==See Also==

===Threads===