A Load Control Mechanism for Data-Flow Machines

The data-flow computer is based essentially on parallel computation. Consequently, it is essential in the realization of such high-level management and control functions as resource management to control the parallelism and parallel expansion. In the first part of this paper, the state and the transition are defined for the process in the dataflow computer, and the method for detecting the number of active state processes Na is discussed. Then a load control method is proposed whereby the processes are executed via the depth-first approach while maintaining Na close to the predetermined threshold Nt. The compatibility between the load control and the load balancing is discussed. As a result of evaluation by the analysis and the simulation at the register transfer level, the following observations were made for the proposed load-control method: (1) Na in a processor is maintained between Nt− 2 and Nt−1, and the depth-first approach is utilized while maintaining the breadth parallelism of approximately 0.75 Nt. (2) The number of resources 0(2k) which has been considered necessary to execute a highly parallel program, is now reduced to 0(k), and the execution speed is improved by approximately 4 percent. (3) By combining the proposed method with the load balancing, the loads are distributed uniformly with the difference of Nt among processors being 3 or less.