I want to find out how much time a certain function takes in my C++ program to execute on Linux. Afterwards, I want to make a speed comparison . I saw several time function but ended up with this from boost. Chrono:

process_user_cpu_clock, captures user-CPU time spent by the current process

Now, I am not clear if I use the above function, will I get the only time which CPU spent on that function?

Secondly, I could not find any example of using the above function. Can any one please help me how to use the above function?

P.S: Right now , I am using std::chrono::system_clock::now() to get time in seconds but this gives me different results due to different CPU load every time.