coresample -- Report the usage of each CPU core for a FirefoxOS or Android device connected via ADB

This is a very simple Python script (I'm a python novice -- pull requests welcome) that uses adb to communicate with the FirefoxOS or Android device connected to your computer via USB cable. It records the contents of /proc/stat, waits 5 seconds, and then records the contents of that file again. By subtracting the first set of numbers from the second set of numbers, it can determine how busy each of the device CPU cores were during the wait period, and it prints a CPU usage report the the console. This is useful, for example, if you want to test an app to see how efficiently is is utilizing the available cores on a given device.

If you want to wait for an interval other than 5 seconds, just specify the number of seconds as an argument on the command line.

$ ./coresample 10
measuring CPU usage over 10.0 seconds
CPU     WORK    BUSY    IDLE    WAIT
0       46%     37%     61%     2%
1       43%     34%     65%     1%
2       8%      6%      94%     0%
3       4%      3%      97%     0%

The output columns are as follows:

• CPU: the core number

• WORK: what percentage of the total work done during the sample period was done on this core

• BUSY: the percentage of the sample time that this core was busy

• IDLE: the percentage of the sample time that this core was busy

• WAIT: the percentage of the sample time that this core was blocked on I/O.