log the cpu time of each request

[alluoshi]

Hello, Apache logs information about each request. We can also log the process ID and the time taken to service this request. But is there any way to log the cpu time for each process as well?

[alluoshi]

After a deep research, there is no simple solution to log the cpu time of each request. We should write our own model. Since Apache logs the time taken to serve each request, so what is the difference between this time and the cpu time of the process?
Is it true to say that the time taken to serve the request = cpu time of the request + other time like I/O time taken by the server + swapping time?