Local versus global schedulers with processor co-allocation in multicluster systems

In systems consisting of multiple clusters of processors which employ space sharing for scheduling jobs, such as our Distributed ASCI 1 Supercomputer (DAS), coallocation, i.e., the simultaneous allocation of processors to single jobs in different clusters, may be required. We study the performance of co-allocation by means of simulations for the mean response time of jobs depending on a set of scheduling decisions such as the number of schedulers and queues in the system, the way jobs with different numbers of components are distributed among these queues and the priorities imposed on the schedulers, and on the composition of the job stream.