Hierarchical Scheduling in Heterogeneous Grid Systems

Grid Scheduling Stages

Grid characteristics must be taken into account in order to perform efficient scheduling. Grid schedulers must make scheduling decisions in a very challenging environment that includes: (1) no control over the resources, since they don’t own them; (2) distributed resources; (3) a dynamic existence of resources (i.e., resources may be added or removed from the grid at any time); (4) a dynamic information collection; (5) heterogeneous resources (jobs must match appropriate resources in order to be executed as requested by the users); and (6) tentative scheduling until the allocation of actual resources (i.e., resources may be taken from the grid before a job actually uses them).

In general, grid scheduling is performed in three stages (Nabrzyski, Schopf, & Weglarz, 2004). First is the resource discovery stage, which produces a set of matched resources. Schedulers are expected to collect static information (e.g., operating systems) from local schedulers or general information systems (GIS), in order to perform job matching. In the next stage, resources are selected (i.e., resource selection stage) from the list obtained during the first stage and are expected to meet user’s imposed constraints (e.g., deadlines). Then schedulers are expected to collect dynamic information (e.g., system load) for the third stage and transfer jobs to selected resources (i.e., job execution stage).