OS-Data-Flow Computers

In sequential processors, control of what to do next resides in the program counter which after the completion of one instruction, normally ...

In sequential processors, control of what to do next resides in the program counter which after the completion of one instruction, normally points to the next instruction to be performed.

Data flow computers can perform many operations in parallel. These machines are said to be data driven because they perform each instruction (potentially simultaneously if enough processors are available) for which the needed data is available. Data flow machines have not been implemented but data flow techniques are already being incorporated in compilers that prepare programs for optimal execution on various kinds of parallel architectures.

An example of how a data flow computer might outperform a sequential computer is show in which a series of assignment statements is evaluated for both a parallel data flow architectures and a sequential architecture.

Assignments: x:=a-c*d+e; 

                        y:=b+d/a; 

                         z:=x+e*y;
Evaluation of a Sequential processor:

1. c*d
2. a-(c*d)
3. (a-(c*d)+e
4. d/a [parents indicate “already evaluated”]
5. b+(d/a)
6. e*y 7 x+(e*y)