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Vectorized Communication

One of the important considerations for message passing on distributed memory machines is the setup time required for sending a message. Typically, this cost is equivalent to the sending cost of hundreds of bytes. Vectorization combines messages for the same source and destination into a single message to reduce this overhead [61][17] Since in Fortran 90D/HPF we are only parallelizing array assignments and forall loops, there is no data dependency between different loop iterations. Thus, all the required communication can be performed before or after the execution of a loop on each of the processors involved as shown in Figure .


zbozkus@
Thu Jul 6 21:09:19 EDT 1995