A Concurrent Dynamic Task Graph

Task graphs are used for scheduling tasks on parallel processors when the tasks have dependencies. If the execution of the program is known ahead of time, then the tasks can be statically and optimally allocated to the processors. If the tasks and task dependencies aren´t known ahead of time (the case in some analysts-factor sparse matrix algorithms), then task scheduling must be performed on the fly. We present simple algorithms for a concurrent dynamic-task graph. A processor that needs to execute a new task can query the task graph for a new task, and new tasks can be added to the task graph on the fly. We present several alternatives for allocating tasks for processors and compare their performance.