Dataflow Processors

Abstract

Control-Flow. The most common computing model (i.e., a description of how a program is to be evaluated) is the von Neumann control-flow computing model. This model assumes that a program is a series of addressable instructions, each of which either specifies an operation along with memory locations of the operands or it specifies (un)conditional transfer of control to some other instruction. A control-flow computing model essentially specifies the next instruction to be executed depending on what happened during the execution of the current instruction. The next instruction to be executed is pointed to and triggered by the program counter PC. This instruction is executed even if some of its operands are not available yet (e.g., uninitialized).

Dataflow stands apart as being the most radical of all approaches to parallelism and the one which has been the least successful…

… If any practical machine based on dataflow ideas and offering real power emerges, it will be very different from what the originators of the concept had in mind.

Maurice V. Wilkes Computing Perspectives (Morgan Kaufmann Publishers, 1995)

…these instructions [of the Intel Pentium Pro] are …executed in dataflow order (when operands are ready)…

Robert P. Colwell and Randy L. Steck A 0.6 μm BiCMOS Processor with Dynamic Execution (Int’l Solid State Circuits Conference, February 1995)