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Benchmarks provide a method of comparing the performance of various subsystems across different chip/system [[Computer architecture|architectures]]. Benchmarking as a part of [[continuous integration]] is called Continuous Benchmarking.<ref>{{cite conference|doi=10.1109/IC2E.2019.00039|chapter-url=https://www.researchgate.net/publication/333918034|chapter=Continuous Benchmarking: Using System Benchmarking in Build Pipelines|year=2019|access-date=2023-12-03|first1=Martin|last1=Grambow|first2=Fabian|last2=Lehmann|first3=David|last3=Bermbach|title=2019 IEEE International Conference on Cloud Engineering (IC2E) |pages=241–246 |isbn=978-1-7281-0218-4 }}</ref>
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== Purpose ==
As [[computer architecture]] advanced, it became more difficult to compare the performance of various computer systems simply by looking at their specifications. Therefore, tests were developed that allowed comparison of different architectures. For example, [[Pentium 4]] processors generally operated at a higher clock frequency than [[Athlon XP]] or [[PowerPC]] processors, which did not necessarily translate to more computational power; a processor with a slower clock frequency might perform as well as or even better than a processor operating at a higher frequency. See [[BogoMips]] and the [[megahertz myth]].
Benchmarks are designed to mimic a particular type of workload on a component or system. Synthetic benchmarks do this by specially created programs that impose the workload on the component. Application benchmarks run real-world programs on the system. While application benchmarks usually give a much better measure of real-world performance on a given system, synthetic benchmarks are useful for testing individual components, like a [[hard disk]] or networking device.
Benchmarks are particularly important in [[CPU design]], giving processor architects the ability to measure and make tradeoffs in [[microarchitecture|microarchitectural]] decisions. For example, if a benchmark extracts the key [[algorithms]] of an application, it will contain the performance-sensitive aspects of that application. Running this much smaller snippet on a cycle-accurate simulator can give clues on how to improve performance.
Prior to 2000, computer and microprocessor architects used [[SPEC]] to do this, although SPEC's Unix-based benchmarks were quite lengthy and thus unwieldy to use intact.
Computer manufacturers are known to configure their systems to give unrealistically high performance on benchmark tests that are not replicated in real usage. For instance, during the 1980s some compilers could detect a specific mathematical operation used in a well-known floating-point benchmark and replace the operation with a faster mathematically equivalent operation. However, such a transformation was rarely useful outside the benchmark until the mid-1990s, when [[RISC]] and [[VLIW]] architectures emphasized the importance of [[compiler]] technology as it related to performance. Benchmarks are now regularly used by [[compiler]] companies to improve not only their own benchmark scores, but real application performance.
CPUs that have many execution units — such as a [[superscalar]] CPU, a [[VLIW]] CPU, or a [[reconfigurable computing]] CPU — typically have slower clock rates than a sequential CPU with one or two execution units when built from transistors that are just as fast. Nevertheless, CPUs with many execution units often complete real-world and benchmark tasks in less time than the supposedly faster high-clock-rate CPU.
Given the large number of benchmarks available, a manufacturer can usually find at least one benchmark that shows its system will outperform another system; the other systems can be shown to excel with a different benchmark.
Manufacturers commonly report only those benchmarks (or aspects of benchmarks) that show their products in the best light. They also have been known to mis-represent the significance of benchmarks, again to show their products in the best possible light. Taken together, these practices are called ''bench-marketing.''
Ideally benchmarks should only substitute for real applications if the application is unavailable, or too difficult or costly to port to a specific processor or computer system. If performance is critical, the only benchmark that matters is the target environment's application suite.
== Functionality ==
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