Instructions per cycle
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In
Explanation
While early generations of CPUs carried out all the steps to execute an instruction sequentially, modern CPUs can do many things in parallel. As it is impossible to just keep doubling the speed of the clock, instruction pipelining and superscalar processor design have evolved so CPUs can use a variety of execution units in parallel - looking ahead through the incoming instructions in order to optimise them. This leads to the instructions per cycle completed being much higher than 1 and is responsible for much of the speed improvements in subsequent CPU generations.
Calculation of IPC
The calculation of IPC is done through running a set piece of code, calculating the number of machine-level instructions required to complete it, then using high-performance timers to calculate the number of clock cycles required to complete it on the actual hardware. The final result comes from dividing the number of instructions by the number of CPU clock cycles.
The number of
The number of instructions executed per clock is not a constant for a given processor; it depends on how the particular
Computer speed
The useful work that can be done with any computer depends on many factors besides the processor speed. These factors include the instruction set architecture, the processor's microarchitecture, and the computer system organization (such as the design of the disk storage system and the capabilities and performance of other attached devices), the efficiency of the operating system, and the high-level design of application software.
For computer users and purchasers, application
See also
References
- OCLC 859555917.
- ^
Hennessy, John L.; Patterson, David A. (2006-11-03). Computer Architecture: A Quantitative Approach. Elsevier. ISBN 978-0-08-047502-8.
- ISBN 978-0-13-410161-3.