Non-Uniform Memory Access (NUMA) is a computer memory design used in multiprocessing, where the memory access time depends on the memory location relative to a processor. Under NUMA, a processor can access its own local memory faster than non-local memory, that is, memory local to another processor or memory shared between processors.
NUMA architectures logically follow in scaling from symmetric multiprocessing (SMP) architectures. Their commercial development came in work by Burroughs (later Unisys), Convex Computer (later Hewlett-Packard), Honeywell Information Systems Italy (HISI) (later Groupe Bull), Silicon Graphics (later Silicon Graphics International), Sequent Computer Systems (later IBM), Data General (later EMC) and Digital (later Compaq, now HP) during the 1990s. Techniques developed by these companies later featured in a variety of Unix-like operating systems, and somewhat in Windows NT.
The first commercial implementation of a NUMA-based Unix system was the Symmetrical Multi Processing XPS-100 family of servers, designed by Dan Gielan of VAST Corporation for Honeywell Information Systems Italy. The tremendous success of the architecture propelled HISI to the #1 spot of Unix vendors in Europe.
Read more about Non-Uniform Memory Access: Basic Concept, Cache Coherent NUMA (ccNUMA), NUMA Vs. Cluster Computing
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