I'm not sure to express this question correctly and I've try to read the man proc, but I can't manage to find a proper answer and I couldn't find a simple way to verify it.
I try to get CPU/RAM consumption for one PID but I don't know how many child processes will be cast by the program and I want to get the total amount of CPU and RAM consumption not just the main process.
I know for fact and experience that /proc/[PID]/io is indeed cumulative through all child processes, but I would like to know and if possible with proof if the same applies to /proc/[PID]/stat.