Why wall clock is very much higher than cpu user/kernel time

Question

In my application written in C++, I am getting below time information.

0.46u CPU user time
1.27s CPU kernel time
41.83s Real wall clock
4% CPU% usage.
0 Major page faults
207848 No. of file system outputs.
100269 minor page faults.
82: No. of times the process was context switched involuntarily.
1297 No. of times that the program was context-switched.

What can be reason for such high wall time, even though there was no major page fault?

Answer 1

Because your code is spending a lot of time doing disk I/O and "waiting":

207848 No. of file system outputs.
100269 minor page faults.
82: No. of times the process was context switched involuntarily.
1297 No. of times that the program was context-switched.

All of these activities (except "no of times process was context switched involuntarily") are indications that your process is doing a lot of waiting around for the hard-disk to deliver something or take on something.

Also the fact that your code is spending more time in Kernel mode then in user mode, is another indication that your code is doing a lot of disk I/O (or other I/O).