Scheduling in HPC Resource Management Systems: Queuing vs. Planning

Nearly all existing HPC systems are operated by resource management systems based on the queuing approach. With the increas- ing acceptance of grid middleware like Globus, new requirements for the underlying local resource management systems arise. Features like ad- vanced reservation or quality of service are needed to implement high level functions like co-allocation. However it is dicult to realize these features with a resource management system based on the queuing con- cept since it considers only the present resource usage. In this paper we present an approach which closes this gap. By assign- ing start times to each resource request, a complete schedule is planned. Advanced reservations are now easily possible. Based on this planning approach functions like diuse requests, automatic duration extension, or service level agreements are described. We think they are useful to increase the usability, acceptance and performance of HPC machines. In the second part of this paper we present a planning based resource man- agement system which already covers some of the mentioned features.