page_title: CPU time
section_title: Unix commands for CPU time
hierarchical_section_title: CPU time / Unix commands for CPU time
caption_attribution_description: English: Display of the en:CPU Time of various en:processes running on en:GNU/en:Linux, a en:Unix-like system.
context_page_description: CPU time is the amount of time for which a central processing unit was used for processing instructions of a computer program or operating system, as opposed to elapsed time, which includes for example, waiting for input/output operations or entering low-power mode. The CPU time is measured in clock ticks or seconds. Often, it is useful to measure CPU time as a percentage of the CPU's capacity, which is called the CPU usage.
  CPU time and CPU usage have two main uses. The first use is to quantify the overall busyness of the system. When the CPU usage is high, the user may experience lag. Such high CPU usage indicates insufficient processing power. Either the CPU needs to be upgraded, or the user experience reduced, for example, by switching to lower resolution graphics or reducing animations.
  The second use, with the advent of multi-tasking, is to quantify how the processor is shared between computer programs. High CPU usage by a single program may indicate that it is highly demanding of processing power or that it may malfunction; for example, it has entered an infinite loop.
caption: top's display of the CPU time of various processes on a Unix-like (GNU/Linux) system
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