What specifically are wall-clock-time, user-cpu-time, and system-cpu-time in UNIX?

by

Wall-clock time is the time that a clock on the wall (or a stopwatch in hand) would measure as having elapsed between the start of the process and ‘now’.

The user-cpu time and system-cpu time are pretty much as you said – the amount of time spent in user code and the amount of time spent in kernel code.

The units are seconds (and subseconds, which might be microseconds or nanoseconds).

The wall-clock time is not the number of seconds that the process has spent on the CPU; it is the elapsed time, including time spent waiting for its turn on the CPU (while other processes get to run).

More Related Contents:

  1. What are file descriptors, explained in simple terms?
  2. sed edit file in place
  3. Remove carriage return in Unix
  4. Canonical vs. non-canonical terminal input
  5. How to use variables in a command in sed?
  6. What does ^M character mean in Vim?
  7. Why is 1/1/1970 the “epoch time”?
  8. What is the difference between a symbolic link and a hard link?
  9. Is there a Unix utility to prepend timestamps to stdin?
  10. sed or awk: delete n lines following a pattern
  11. Grep for literal strings
  12. Use grep –exclude/–include syntax to not grep through certain files
  13. How do I use the nohup command without getting nohup.out?
  14. How to extract just plain text from .doc & .docx files? [closed]
  15. nginx error connect to php5-fpm.sock failed (13: Permission denied)
  16. Explain awk command
  17. Spinlock versus Semaphore
  18. Why always ./configure; make; make install; as 3 separate steps?
  19. What is special about /dev/tty? [closed]
  20. Unix:merge multiple CSV files with same header by keeping the header of the first file
  21. Understanding concurrent file writes from multiple processes
  22. unix command line execute with . (dot) vs. without
  23. How to strip leading “./” in unix “find”?
  24. Using grep for multiple search patterns
  25. When using os.execlp, why `python` needs `python` as argv[0]
  26. Display filename before matching line
  27. How to move or copy files listed by ‘find’ command in unix?
  28. How do I change a shell scripts character encoding?
  29. What are the dark corners of Vim your mom never told you about? [closed]
  30. In a unix shell, how to get yesterday’s date into a variable?

Leave a Comment