Flops redirects here. For the poker term, see flop (poker). For commercial failures, see List of commercial failures.

In computing, FLOPS is an abbreviation of Floating Point Operations Per Second. This is used as a measure of a computer's performance, especially in fields of scientific calculations that make heavy use of floating point calculations.

One should speak in the singular of a FLOPS and not of a FLOP, although the latter is frequently encountered. The final S stands for Second and does not indicate a plural.

The performance spectrum

Computing devices exhibit an enormous range of performance levels in floating-point applications. Thus it makes sense to introduce larger units than the FLOPS; the standard SI decimal prefixes are used for this purpose. For example, a cheap but modern desktop computer can make billions of floating point operations per second, so its performance is in the range of a few GFLOPS (GigaFLOPS, 10⁹ FLOPS).

Today's most powerful supercomputers have speeds measured in TFLOPS (TeraFLOPS, 10¹² FLOPS). The fastest computer in world as of November 5, 2004 was the IBM Blue Gene supercomputer, measuring 70.72 TFLOPS. This supercomputer was a prototype of the Blue Gene/L machine IBM is building for the Lawrence Livermore National Laboratory in California. During a speed test on 24th March 2005, it was rated at 135.5 teraflops. Blue Gene's new record was achieved by doubling the number of current racks to 32. Each rack holds 1,024 processors, yet the chips are the same as those found in high-end computers on the High Street. The complete version will have a total of 64 racks and a theoretical speed measured at 360 TeraFLOPS.

The computers that generated Lord of the Rings characters and places - Gollum, the Balrog, and Middle Earth - are now available for hire, for example. The cluster of 1,008 computers in New Zealand can be rented on-demand, on a per hour, per processor basis.

Already the supercomputer is being used to design a super yacht and test gene sequencing algorithms.

Since the original supercomputer, the Cray-1, was set up at Los Alamos National Laboratory, US, in 1976, computational speed has jumped by 500,000 times.

The Cray-1 was able to do 80 megaflops (80 million operations a second).

Pocket calculators are at the other end of the performance spectrum. Each calculation request to a typical calculator requires only a single operation, so there is rarely any need for its response time to exceed that needed by the operator. Any response time below 0.1 second is experienced as instantaneous by a human operator, so a simple calculator could be said to operate at about 10 FLOPS.

Humans are even worse floating-point processors. If it takes a person a quarter of an hour to carry out a pencil-and-paper long division with 10 significant digits, that person would be calculating in the mFLOPS (Milli-) range.

FLOPS as a measure of performance

In order for flops to be useful as a measure of floating-point performance, a standard benchmark must be available on all computers of interest. An example is the LINPACK benchmark.

FLOPS in isolation are arguably not very useful as a benchmark for modern computers. There are many other factors in computer performance other than raw floating-point computation speed, such as interprocessor communication, cache coherence, and the memory hierarchy.

For ordinary (non-scientific) applications, integer operations (measured in MIPS) are far more common. Measuring floating point operation speed, therefore, does not predict accurately how the processor will perform on just any problem. However, for many scientific jobs such as analysis of data, a FLOPS rating is effective.