Instruction Pipeline - Illustrated Example

Illustrated Example

To the right is a generic pipeline with four stages:

  1. Fetch
  2. Decode
  3. Execute
  4. Write-back

The top gray box is the list of instructions waiting to be executed; the bottom gray box is the list of instructions that have been completed; and the middle white box is the pipeline.

Execution is as follows:

Time Execution
0 Four instructions are waiting to be executed
1
  • the green instruction is fetched from memory
2
  • the green instruction is decoded
  • the purple instruction is fetched from memory
3
  • the green instruction is executed (actual operation is performed)
  • the purple instruction is decoded
  • the blue instruction is fetched
4
  • the green instruction's results are written back to the register file or memory
  • the purple instruction is executed
  • the blue instruction is decoded
  • the red instruction is fetched
5
  • the green instruction is completed
  • the purple instruction is written back
  • the blue instruction is executed
  • the red instruction is decoded
6
  • The purple instruction is completed
  • the blue instruction is written back
  • the red instruction is executed
7
  • the blue instruction is completed
  • the red instruction is written back
8
  • the red instruction is completed
9 All four instructions are executed

Read more about this topic:  Instruction Pipeline

Famous quotes containing the word illustrated:

    “Women ... are completely alone, though they were born and bred upon this soil, as if they belonged to another class in creation.”
    —“Jennie June” Croly 1829–1901, U.S. founder of the woman’s club movement, journalist, author, editor. F, Demorest’s Illustrated Monthly Mirror of Fashions, pp. 363-4 (December 1870)

    “The creation of “strong-minded” women, so-called, is due to the individualism of men, to the modern selfish and speculative spirit which absorbs everything within itself and leaves women nothing but self-assertion for their protection and support.”
    —“Jennie June” Croly 1829–1901, U.S. founder of the woman’s club movement, journalist, author, editor. Demorest’s Illustrated Monthly and Mirror of Fashions, p. 44 (February 1870)