Pipelining (OCR A Level Computer Science)

Pipelining

What is Pipelining?

• Pipelining is the process of carrying out multiple instructions concurrently

• Each instruction will be at a different stage of the fetch-decode-execute cycle

• One instruction can be fetched while the previous one is being decoded and the one before is being executed

• In the case of a branch, the pipeline is flushed

• This table shows which stage each instruction is at during each step:

• While one instruction is being executed, the next instruction will be decoded and the following instruction will be fetched

How Does Pipelining Improve Processor Performance?

• Pipelining reduces latency 

• The CPU is not idle while waiting for the next instruction which increases the speed of execution

• The next instruction is fetched while the current one is decoded/executed

• All parts of the processor can be used at any instance in time