| slovo | definícia |
data flow
(foldoc) | data flow
A data flow architecture or language performs a
computation when all the operands are available. Data flow is
one kind of data driven architecture, the other is {demand
driven}. It is a technique for specifying {fine-grain
concurrency}, usually in the form of two-dimensional graphs in
which instructions that are available for concurrent execution are
written alongside each other while those that must be executed in
sequence are written one under the other. Data dependencies
between instructions are indicated by directed arcs. Instructions
do not reference memory since the data dependence arcs allow data
to be transmitted directly from the producing instruction to the
consuming one.
Data flow schemes differ chiefly in the way that they handle
re-entrant code. Static schemes disallow it, dynamic
schemes use either "code copying" or "tagging" at every point
of reentry.
An example of a data flow architecture is MIT's VAL
machine.
|
| | podobné slovo | definícia |
data flow analysis
(foldoc) | data flow analysis
A process to discover the dependencies between
different data items manipulated by a program. The order of
execution in a data driven language is determined solely by
the data dependencies. For example, given the equations
1. X = A + B
2. B = 2 + 2
3. A = 3 + 4
a data-flow analysis would find that 2 and 3 must be evaluated
before 1. Since there are no data dependencies between 2 and
3, they may be evaluated in any order, including in parallel.
This technique is implemented in hardware in some
pipelined processors with multiple functional units. It
allows instructions to be executed as soon as their inputs are
available, independent of the original program order.
(1996-05-13)
|
data flow diagram
(foldoc) | Data Flow Diagram
DFD
A graphical notation used to describe how data
flows between processes in a system. Data flow diagrams are
an important tool of most structured analysis techniques.
(http://smartdraw.com/resources/centers/software/dfd.htm).
(2003-05-17)
|
|