Glossary

Access time - The time a program or device takes to locate a single piece of information and make it available to the computer for processing.

Average seek time - Refers to the time a program or device takes to locate a particular piece of data. For disk drives, the terms seek time and access time are often used interchangeably. However, the access time is often longer the seek time because it includes a brief latency period.

Dhrystone - Developed in 1984 by R.P. Wecker, Dhrystone is a benchmark program written in C or Pascal (and now even in Java) that tests a system's integer performance. The program is CPU bound, performing no I/O functions or operating system calls. Dhrystones per secondis the metric used to measure the number of times the program can run in a second.

FLOPS - short for floating-point operations per second, a common benchmark measurement for rating the speed of microprocessors. Floating-point operations include any operations that involve fractional numbers. Such operations, which take much longer to compute than integer operations, occur often in some applications. MFLOPS is equal to one million floating-point operations per second. GFLOPS is equal to one billion floating-point operations per second.

MIPS - acronym for million instructions per second. A old measure of a computer's speed and power, MIPS measures roughly the number of machine instructions that a computer can execute in one second. However, different instructions require more or less time than others, and there is no standard method for measuring MIPS. In addition, MIPS refers only to the CPU speed, whereas real applications are generally limited by other factors, such as I/O speed. A machine with a high MIPS rating, therefore, might not run a particular application any faster than a machine with a low MIPS rating. For all these reasons, MIPS ratings are not used often anymore.

FPS - short for Frames Per Second. a measure of how much information is used to store and display motion video. Defines the speed of graphical subsystem.

Random access/read speed - refers to the ability to access/read data at random.

Whetstone - benchmark program that tests a system's fractional numbers performance (floating-point). The test is CPU bounded and doesn't perform the I/O calls.


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