Aspects of the parallel program execution: work, time and the current state

The main focus in debugging and monitoring program execution is given as the notion of time. In particular, the progress of the execution, which is interpreted as useful computation, is addressed. The authors describe two interpretations, or views, of the causality graph which complement each other in the display of the propagation of the execution. The causality graph is the graph constructed from the partial order which reflects the execution of a parallel program. Additional processing of the causality graph is necessary in order to retrieve these views. This additional processing is essential since the complete, detailed display of the graph is unrealistic for programs of reasonable size. From the causality graph two notions are extracted: the notion of time slice and the notion of work. The definition of a unit of work and what this notion means for the application is provided by the user, and serves as an additional attribute of computation and resource nodes in the graph. These nodes are used for the generation of the views described.<
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