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