Suppose we run program P in a computer system using the Linu

Suppose we run program P in a computer system using the Linux operating system. We use the Linux time command to collect some time measurements while P is running. The output from time is, real 53m27.589s user 24m41.850s system 1m3.337s What was the execution time of P? What was the user CPU time of P? What was the system CPU time of P? How much time during the execution of P did the system spend not executing the instructions of P nor OS instructions on behalf of P? List and describe one factor or component of the time from exercise d, i.e., name one thing the system might have been doing during this time period.

Solution

a. The execution time of P was user+system I.e.

25m45.187s

b. 24m41.850s was the user CPU time of P

c. The system CPU time P was 1m3.337s

d. It\'s real-(user+system) I.e. 27m42.399s

e. Real is a wall clock time - time from start to finish of the call. This is all elapsed time including time slices used by other processes and time the process spends blocked may be the waiting time to complete its I/O.