Virtual Tasks for the PACLIB Kernel

We have extended the task management scheme for the parallel computer algebra package PACLIB. This extension supports "virtual tasks" (tasks that are not yet executable) which are created more efficiently than "real tasks" (tasks that are immediately scheduled for execution). Virtual tasks become real only when the system is idling or existing real tasks can be recycled. Consequently, the overhead for task creation and synchronization but also the memory requirements of a parallel program may be reduced. We analyze the system theoretically and experimentally and compare it with another virtual task package. In part our observations and conclusions are significantly different. Keywords: Light-weight processes, lazy task creation, scheduling, shared memory computers, computer algebra. Supported by the Austrian Science Foundation (FWF) grant S5302-PHY "Parallel Symbolic Computation ". 1 Introduction 1 1 Introduction The purpose of this paper is twofold: first it reports the extensi..