Characterizing memory hot spots in a shared memory MIMD machine
Raymond R. Glenn, Daniel V. Pryor, John M. Conroy, Theodore J. Johnson · 1991
This paper analyzes two memory hot spot problems associated with massively parallel MIMD computers.The jirst is the memory stride problem, which is similar to stride problems found in existing supercomputers.Pseudo-random interleaving, as proposed by Norton and Melton, is the preferred solution.The second hot spot problem occurs in designs that use two separate memory accesses to lock and unlock critical sections (split transaction) and employ a jirst comeljirst serve queuing mechanism for shared memory locations.A bistabilip in throughput brought about by these conditions is analyzed and experimentally demonstrated.Simple equations are presented which predict the throughput at a critical section of code as a function of the number of applied threads.These equations also express the maximum number of threads that can safely be applied without the possibility of stalling.