Parallel Computing Paradigms

Shared Memory



 EXAMPLE:
Cray YMP C/J 90
SGI Origin 200/2000
Sun E10000
SMP Intel-based computers (Dell, Unisys)

Advantages:
Easy to program applications (POSIX threads).

Disadvantages:
  • Expensieve hardware and maintenance
  • Memory latency due to shared mem segments and semaphores
  • Performance scales poorly with the number of CPUs

    • Message Passing


    		 EXAMPLE:
    Cray T3E
    Unix (Linux) clusters

    Advantages:
  • Cheap and fast hardware: CPU speed doubles every 18 months (Moore's law)
  • Fast network interconnect: Ethernet (1 - 10 GBit/sec), Myranet (2 GBit/sec), Infiniband (10 GBit/sec )
  • Performance scales well with the number of CPUs

    Disadvantages:
    Hard to program applications (MPI)
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