What is the CPU Clock Rate? known as speed, frequency measured in Hertz (Hz)

About

CPU's are marching forward at the frequency of the clock.

This frequency is also known as the:

• clock speed
• clock rate
• or CPU frequency

The clock rate is the speed at which a microprocessor (CPU) executes instructions.

Every computer contains an internal clock (a clock generator) that regulates the rate at which instructions are executed by sending a signal (tick) and synchronizes all the various computer components.

Example

A 100Mhz processor will receive 100,000,000 clock ticks every second.

Increase

CPU clock speeds are barely increasing (Moores law hits the roof),

Units (Mhz to ns)

• Rate often measured in:
  • MHz = millions of cycles/second
  • Ghz = billions of cycles/second
• Time often measured in ns (nanoseconds)

<MATH> \begin{array}{rl} {X} \mbox{ MHz } && = && \frac{\displaystyle 1000}{\displaystyle X} \mbox{ ns} \\ 500 \text{ MHz} && \approx && 2 \text{ ns clock} \end{array} </MATH>

Factor

Performance

The CPU requires a fixed number of clock ticks to execute each instruction. The faster the clock, the more instructions the CPU can execute per second.

It's the most important factor in the CPU performance (ie number of instruction by second).

Power

Clock speed is the biggest contributor to power. Chip manufactures (Intel, esp.) pushed clock speeds very hard in the 90s and early 2000s. Doubling the clock speed increases power by 2-8x. Clock speed scaling is essentially finished. What’s Next: Parallelism. This is all the rage right now (multi-processor).