Linux clock time, user CPU time, System CPU time.

Have seen a few times before the concept, but still always remember, simply write it down, easy to see in the future ~

The so-called clock time is also called the wall clock time, it is the total number of clocks that the process is running, and its value is related to how many processes are running concurrently in the system, although it is generally measured when there are no other activities in the system when discussing clock time.

User CPU Time: Is the time spent executing user instructions.

System CPU Time: The so-called system, we know that is the time to execute in the kernel, yes, that is, the process of executing the kernel program experience time.

It is not difficult to see these three times of a process, as long as you execute the command time, such as:

1. [Email protected]:~/temp$ time./test
2. Sdga
3. S d G A
4. Above is the test program.
5. Real 0m4.019s//clock time
6. User 0m0.004s//Subscriber CPU Time
7. SYS 0m0.000s//System CPU time

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Linux clock time, user CPU time, System CPU time.