Shared memory architecture

In computer architecture, shared memory architecture (SMA) refers to a multiprocessing design where several processors access globally shared memory.^[1]

Shared memory architectures may use:^[1]

Uniform Memory Access (UMA): all the processors share the physical memory uniformly.

Non-Uniform Memory Access (NUMA): memory access time depends on the memory location relative to a processor.

Cache-only memory architecture (COMA): the local memories for the processors at a node is used as cache.

In a SMA system processors communicate by reading and writing memory locations.^[1] The two key problems in scaling an SMA system are:^[1]

performance degradation due to "contention" when several processors try to access the same memory location.

lack of "coherence" if memory is cached and goes out of synch with the original values as modifications take place.

See also

Shared memory

References

^ ^a ^b ^c ^d Advanced computer architecture and parallel processing by Hesham El-Rewini et al. 2005 ISBN 978-0-471-46740-3 pages 77-80

Computer architecture