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:
calendar timeis 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.
amount of timeis 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.
Processor timeis 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.