Pipelining

Execution of an individual instruction is inherently a process consisting of several steps, each depending on the previous one.

How can we reduce CPI?

  $\mbox{$\bullet$}$

Design the instruction set so few steps are needed.

  $\mbox{$\bullet$}$

Improve the compiler so faster instructions are used in preference to slower ones.

  $\mbox{$\bullet$}$

Start on the next instruction before the preceding one has finished

$\hookrightarrow$

that is, pipelining