【Linux】Time Basics

查看man时，发现有的地方是CPU Time有的地方是Processor Time，想区分下，就发现了如下极度蛋疼的不同的时间称呼，原文链接为Time Basics:The GNU C Library。为保留原滋原味的蛋疼体验，下面大部分内容仍保留英文原版内容不做翻译:

• 日常时间点、绝对时间值
  A calendar time is a point in the time continuum, for example November 4, 1990 at 18:02.5 UTC. Sometimes this is called “absolute time”.
  We don’t speak of a “date”, because that is inherent in a calendar time.

• 时光(间隔时间、间期，自己想任性的用时光这个词 <(￣︶￣)> …)
  An interval is a contiguous part of the time continuum between two calendar times, for example the hour between 9:00 and 10:00 on July 4, 1980.

• 时长、时间量、时间跨度
  An elapsed time is the length of an interval, for example, 35 minutes. People sometimes sloppily use the word “interval” to refer to the elapsed time of some interval.

• 时间总量、时间总长度
  An amount of time is a sum of elapsed times, which need not be of any specific intervals. For example, the amount of time it takes to read a book might be 9 hours, independently of when and in how many sittings it is read.

• 周期
  A period is the elapsed time of an interval between two events, especially when they are part of a sequence of regularly repeating events.

• CPU时间
  CPU time is like calendar time, except that it is based on the subset of the time continuum when a particular process is actively using a CPU. CPU time is, therefore, relative to a process.

• 处理器时长
  Processor time is an amount of time that a CPU is in use. In fact, it’s a basic system resource, since there’s a limit to how much can exist in any given interval (that limit is the elapsed time of the interval times the number of CPUs in the processor).

• People often call this CPU time*, but we reserve the latter term in this manual for the definition above.