A simulation study of the CRAY X-MP memory system

Journal Article · Tue Jul 01 00:00:00 EDT 1986 · IEEE Trans. Comput.; (United States)

DOI:https://doi.org/10.1109/TC.1986.1676802· OSTI ID:5641123

Cheung, T; Smith, J E

One of the significant differences between the CRAY X-MP and its predecessor, the CRAY-1S, is a considerably increased memory bandwidth for vector operations. Up to three vector streams in each of the two processors may be active simultaneously. These streams contend for memory banks as well as data paths. All memory conflicts are resolved dynamically by the memory system. This paper describes a simulation study of the CRAY X-MP interleaved memory system with attention focused on steady state performance for sequences of vector operations. Because it is more amenable to analysis, the authors first study the interaction of vector streams issued from a single processor. They identify the occurrence of linked conflicts, repeating sequences of conflicts between two or more vector streams that result in reduced steady state performance. Both worst case and average case performance measures are given. The discussion then turns to dual processor interactions. Finally, based on our simulations, possible modifications of the CRAY X-MP memory system are proposed and compared. These modifications are intended to eliminate or reduce the effects of linked conflicts.

• Research Organization: Dept. of Electrical and Computer Engineering, Univ. of Wisconsin, Madison, WI 53706
• OSTI ID: 5641123
• Journal Information: IEEE Trans. Comput.; (United States), Vol. C-35:7
• Country of Publication: United States
• Language: English

Related Subjects

99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
CRAY COMPUTERS
MEMORY DEVICES
COMPUTERIZED SIMULATION
SUPERCOMPUTERS
ARRAY PROCESSORS
MODIFICATIONS
PERFORMANCE
STEADY-STATE CONDITIONS
VECTOR PROCESSING
COMPUTERS
DIGITAL COMPUTERS
PROGRAMMING
SIMULATION
990200* - Mathematics & Computers