Abstract

This paper describes the design and use of a new tool for profiling the parallelism present in annotated functional programs. One component of the tool is a compiler modified to produce programs that run in quasi-parallel on an ordinary workstation. A quasi-parallel implementation has several advantages for profiling parallelism. Firstly, it allows the programmer to concentrate solely on the details of parallel program design by abstracting away from the details of parallel machine design. No attempt is made to simulate the organisation or workings of any particular parallel 2 computer. Secondly, a parallel program's behaviour is reproducible at different times and on different computers --- a very important property when investigating the causes of poor performance. Finally, it is comparatively easy to experiment with different parallel primitives and evaluation strategies, and to generate different kinds of profiling information. The other component of the tool aids understanding of profiling information by converting it to various different graphical forms. We are specifically interested in lazy parallel functional programs. It can be hard to write an efficient lazy sequential program, and it is at least as hard to write a lazy parallel program as it is to write a lazy sequential one. So, by using a quasiparallel implementation and ignoring the extra constraints imposed by a parallel computer, we are by no means avoiding "all the hard problems". 2 Profiling Parallelism

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