Compile-time Loop Splitting for Distributed Memory ... - Stanford AI Lab

Chapter 2
Array Management in
Multiprocessors
Before describing the details of loop splitting, this thesis presents some background
information on multiprocessor array management. Specifically, the multiprocessors
discussed here are distributed memory machines. This section helps to give perspective on
both the complexities of array references and the benefits of loop splitting in reducing
these expressions.
2.1 Introduction
Multiprocessors are designed with the hope that many computers can perform the job of
one computer in less time. Ideally hidden from the user, a program is run on a
communication network of processor-memory pairs, as seen in Figure 2-1. However, to
utilize more than one processor, a system of distributing the job among the processing
elements must first be devised. In the most ideal case, a load-balanced partition – an
equitable division of work among all processors – is found; and a multiprocessor terminates
a program in Ia€ �� the time of a uniprocessor, where € is the number of processors.
However, partitioning problems, data dependencies, processor communication, and
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