What is pipelining?

We are going to discuss an important topic related to parallel processing of computer organization and architecture - "Pipelining" 

 

Pipelining is a method in which a sequential task is decomposed into the subtasks and then each of the subtask is executed in a specialized dedicated stage while operating concurrently with all other stages. 

Every stage performs partial processing of the task that it is supposed to do. And then the result obtained is passed to the next stage in pipeline. Once the instruction has passed through all the stages, the final result is obtained.

 

All the stages in pipelining are synchronized by a common clock.

Each of the stages can be understood as a combinational circuit that keeps performing arithmetic or logic operations over the data stream flowing through the pipelining stages. Each stage is seperated by high-speed interface latches (collection of registers).

 

Performance of pipeline processor

Performance of a pipeline processor is measured with help of following parameters:

• efficiency→ The efficiency of a linear pipeline is measured by the percentage of busy time-space spans over the total time-space span, which equal the sum of all busy and idle time-space spans.
• throughput→ The number of tasks that can be completed by a pipeline per unit time is known as throughput. 
• speed-up→ speed-up = (time to execute n tasks in k-stage non-pipeline processor)/(time to execute n tasks in k-stage pipeline processor)

Classification of pipeline processor

Pipeline processors are classified as:

1. Arithmetic pipeline
2. Instruction pipeline
3. Processor pipeline