How Processors Are Measured

Processors are measured in terms of performance and power consumption.

Processors, also known as CPUs, for central processing units, and microprocessors, are the central component of every computer. Their job is to calculate, move data between memory locations and perform logical comparisons. Users measure them in ways mainly concerned with how fast they get work done. Other measurements deal with memory size and energy consumption.

Clock Frequency

All computers have a master clock circuit that sends out a steady stream of electronic impulses, synchronizing all the activity in the system. Generally speaking, the faster the clock, the more powerful the processor, though a more sophisticated processor with a lower clock speed might get more work done than a simpler one with a faster clock. But because the clock speed is a single, handy number, it draws attention. In 2011, processor clock frequencies range from a few MHz to 4 GHz.

MIPS and FLOPS

Every processor has a set of built-in instructions that perform various tasks from arithmetic to data storage. Every software program you use is composed of these instructions. Another measure of speed, MIPS, or millions of instructions per second, gauges how many of these instructions the processor typically performs in a second. By comparing the MIPS numbers of similar processors, you can get a good idea of their relative performance. Contemporary processors measure between a few dozen and a few thousand MIPS.
A similar measurement, floating point operations per second, or FLOPS, measures a processor’s ability to do scientific calculations. A floating point number has a decimal and an exponent, such as 1.059 x 10^-2; you frequently encounter them in scientific math involving very large or small numbers. Processors calculate at a rate of billions to trillions of FLOPS.

Address Size

Processors do not work alone inside a computer; they must have random access memory, or RAM, to function. The maximum amount of memory a processor can use makes a big difference in its level of sophistication: a processor with a few kilobytes of memory can run a toaster, but it takes gigabytes of RAM to run Web browsers, databases and other modern software. Computer chip makers measure address size in bits, the smallest being 16 and the largest measuring 64. A 16-bit processor can access 64K bytes of memory. Sixty-four-bit processors manage up to 18 exabytes, or 18 billion billion characters.

Power Consumption

With the increase in the use of mobile devices, including smartphones, tablets and notebook computers, a processor’s power consumption directly affects its usefulness: a fast processor is no good in a phone if it runs the battery down in a few minutes. On the other hand, processors in server computers simply focus on MIPS and clock speed; for them, power consumption is secondary. The processors in cell phones consume under 1 watt of power; those in servers use over 100 watts. Newer processors tend to be more energy-efficient than their predecessors.

Cores

Some processors have multiple cores to handle larger workloads. A core contains a processor's essential operating circuits, so each core does its own arithmetic and logic independent of the others. A processor with two cores can work on two tasks at once. A typical multicore computer processor has two, four, six or eight cores; however, graphics processors now sport hundreds of cores.

References

• PassMark Software: CPU Benchmarks
• Maxxpi: Top 10 MIPS
• SImetric: Metric System Prefixes
• Nvidia: Tesla Personal Supercomputer