Microarchitecture

computer-architecture

Definition

Microarchitecture

Microarchitecture is the internal implementation of a instruction set architecture.

Different microarchitectures can implement the same architecture in different ways, for example as a single-cycle, multicycle, or pipelined processor.

• Single-cycle: each instruction executes in one clock cycle.
• Multicycle: each instruction is split into a series of shorter steps.
• Pipelined: each instruction is split into stages, and multiple instructions are processed at once.

Processor Performance

The execution time of a program can be expressed as:

$$\text{Execution time}=\#\text{instructions}\times \mathrm{CPI}\times \text{clock period}$$

where:

• CPI is the average number of clock cycles per instruction.
• clock period is the duration of one clock cycle.
• IPC is the reciprocal of CPI.

A microarchitecture can improve performance by reducing CPI, reducing the clock period, or both.