HELP! * YELLOW=global GREY=local Global HTML version of Foils prepared July 6 1996

Foil 13 Granularity of Parallel Components

From HPCC Current Status: Hardware MPP Trip to China -- July 12-28,96. by Geoffrey Fox * See also color IMAGE

Coarse-grain: Task is broken into a handful of pieces, each executed by powerful processors. Pieces, processors may be heterogeneous. Computation/ communication ratio very high -- Typical of Networked Metacomputing
Medium-grain: Tens to few thousands of pieces, typically executed by microprocessors. Processors typically run the same code.(SPMD Style) Computation/communication ration often hundreds or more. Typical of MIMD Parallel Systems such as SP2 CM5 Paragon T3D
Fine-grain: Thousands to perhaps millions of small pieces, executed by very small, simple processors (several per chip) or through pipelines. Processors typically have instructions broadcasted to them.Computation/ Communication ratio often near unity. Typical of SIMD but seen in a few MIMD systems such as Dally's J Machine or commercial Myrianet (Seitz)
Note that a machine of one type can be used on algorithms of the same or finer granularity


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