Hi Otis,
I understand that your query is regarding the difference in “Lines where the most time was spent” and “Children (called functions)” time presented by MATLAB profiler.
The discrepancy between the time reported for the line in function A that calls function B (30.345 seconds) and the time spent within function B itself (30.162 seconds) can be attributed to the overhead involved in calling the function. This overhead may include:
- Time to invoke the function: The process of setting up the call to function B, which includes preparing the arguments, stack frame, and handling the return address.
- Profiling overhead: The profiler itself adds some overhead, as it has to record the entry and exit points of the functions being called.
- Time to return from the function: After function B completes, there is some time spent to clean up and return to function A.
The difference (30.345 - 30.162 = 0.183 seconds) is relatively small compared to the total execution time but is nonetheless significant in profiling. This difference is the additional time spent by function A in managing the call to function B, which is not part of the actual execution time of the code within function B.
In summary, the reason for the difference in these two numbers is indeed the overhead associated with the function call mechanism in MATLAB.
