- Slides: 24
• A linear pipeline processor is constructed with K stages (processing stages). • Inputs are fed to the pipeline at the first stage S 1 • The processed results are passed from stage Si to stage Si+1 for all i=1, 2, 3, …. K-1 • The final result is obtained at last stage Sk
• The pipeline consists of cascade of processing stages The stages are combinational circuits performing arithmetic or logic operations over the data stream flowing through the pipe. • The stages are separated by a high-speed interface latches The latches are fast registers for holding the intermediate results between the stages. • Information flows between adjacent stages are under the control of a common clock applied to all the latches simultaneously.
• The utilization pattern of successive stages in a synchronous pipeline is specified by a reservation table. •
• A reservation table represents the flow of data through the pipeline for one complete evaluation of a given function. • A marked entry in the (i, j)th square of the table indicates that stage Si will be used j time units after the initiation of the function evaluation. • For a unifunctional pipeline, pipeline one can simply use an “x” mark the table entries. • For a multifunctional pipeline, pipeline different marks are used for different functions, such as the A’s and B’s in the two reservation table for the sample pipeline.
NON LINEAR PIPELINE PROCESSOR: • Dynamic • Multifunction • Allows feed back and feed forward connections , in addition to the streamline connections. • More than one output; the output of the pipeline is not necessarily from the last stage.
A Three Stage Pipeline
• Non linear Pipeline Processors • In some computations, the outputs of the pipeline are fed back as future inputs i. e input may depend on previous outputs. • Thus pipeline with feedback may have a nonlinear flow of data. • Proper sequencing with nonlinear , data flow may enhance the pipeline efficiency.
• Consider a Sample Pipeline that has a structure with feed forward and feedback connections as shown in fig. • This pipeline is dual functional, functional denoted as function A and B. B We will number the pipeline stages S 1, S 2, . . . Sz from input end to output end. • A feed forward connection connects a stage Si to Stage Sj such that j>=i+2 and a feedback connection connects a stage Si to Stage Sj such that j<=i. • Thus a pure linear pipeline is pipeline without any feedback or feed forward connections.
Difference Between Linear and Non. Linear pipeline: Linear Pipeline Linear pipeline are static pipeline because they are used to perform fixed functions Linear pipeline allows only streamline connections. It is relatively easy to partition a given function into a sequence of linearly ordered sub functions. Non-Linear Pipeline Non-Linear pipeline are dynamic pipeline because they can be reconfigured to perform variable functions at different times. Non-Linear pipeline allows feedforward and feedback connections in addition to the streamline connection. Function partitioning is relatively difficult because the pipeline stages are interconnected with loops in addition to streamline connections.
Linear Pipeline Non-Linear Pipeline The Output of the pipeline is produced from the last stage. not necessarily produced from the last stage. The reservation table is trivial The reservation table is nonin the sense that data flows in trivial in the sense that there linear streamline. is no linear streamline for data flows. A single Reservation table is needed for the evaluation of different functions. Multiple Reservation tables can be generated for the evaluation of different functions.