The hardware

There are various hardware components that may impact the performance of software in different ways. The processors, caches, memory subsystem, I/O subsystems, and so on, all have varying degrees of performance impact depending upon the use cases. In the following sections we look into each of those aspects.

Processors

Since about the late 1980s, microprocessors have been employing pipelining and instruction-level parallelism to speed up their performance. Processing an instruction at the CPU level consists of typically four cycles: fetch, decode, execute, and writeback. Modern processors optimize the cycles by running them in parallel—while one instruction is executed, the next instruction is being decoded, and the one after that is being fetched, and so on. This style is called instruction pipelining.

In practice, in order to speed up execution even further, the stages are subdivided into many shorter stages, thus leading to deeper super-pipeline architecture. The length...