英文Framework.pdfVIP

Issues in Parallel Programming Environments NB MacDonald MG Norman Edinburgh Parallel Computing Centre Department of Computer Science University of Edinburgh January Abstract We are interested in the problem of providing environments to parallel pro grammers which provide a go o d abstraction from the underlying machine architecture and yet still allow ecient execution on architectures with non uniform memory lo cality We do not suggest there might b e a readymade solution to this problem or that any one solution will b e applicable for all applications For the purp ose of this pap er we are merely interested in out lining the tradeos and explaining how they are dealt with in a numb er of existing parallel programming environments Framework We shall use the terminology of Sarkar Sarkar and others to describ e the various phases involved in compiling a program for parallel execution The rst of these de tection of parallelism involves deriving a maximally parallel description of the program in terms of a directed acyclic graph of tasks satisfying precedence relations by commu nication on termination In the second partitioning stage tasks are merged to form gr ains which will execute on the same pro cessor The nal stage mapping allo cates these grains to particular pro cessors We can consider the available programming environments in the light of the facilities they provide for Detecting parallelism Control of partitioning Control of mapping Abstraction from communication It is our intention to explain the way these facilities have b een made available in a n