What Is "cpu Time" (using Android's Ps -x)?

So I'm trying to write a Java function that gathers CPU time for processes, and compares them to prior readings to determine the CPU time a process has demanded since the last samp

Solution 1:

The values are CPU and system time in clock ticks. The definition can be found in the man 5 proc text from a desktop system:

          utime %lu   Amount of time that this process has been  scheduled
                      in  user  mode,  measured  inclock ticks (divide by
                      sysconf(_SC_CLK_TCK).   This  includes  guest  time,
                      guest_time  (time  spent  running a virtual CPU, see
                      below), so that applications that are not  aware  of
                      the  guest  time  field  donot lose that time from
                      their calculations.

          stime %lu   Amount of time that this process has been  scheduled
                      in  kernel  mode, measured inclock ticks (divide by
                      sysconf(_SC_CLK_TCK).

The values are tracked per-thread, so you should be using ps -t -x to see all threads in each process. Without -t you're just looking at the stats for the main thread, which may be why your numbers don't add up.