> an energy aware time command


this project was motivated by wanting to measure the overall energy consumption and efficiency of programs.

it uses a simple approach that sums the total power used over the duration of a command, which is energy.

measurements are taken from the wall outlet a computer is plugged into using this smart plug.

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some example usage

outputs of etime are similar to the standard time command. only information about energy measurements is added.

nuances of the program are detailed in the project description.

interesting measurements to make might include sorting programs or the idle baseline of a system:

$ ./etime sleep 12
       12.00 real         0.00 user         0.00 sys
      922.63 joules      76.87 watts      100.0% sure

hacking the hardware

the plug taking measurements probably wasn’t meant to be polled.

this is most apparent in occasional missing values from api responses, hence the sureness score.

and also the lack of official documentation.

but being an api that can be accessed from the web, the endpoints were documented anyways and are now relied upon.

understanding energy and power

the original maintainer of this project had forgotten the difference between measurements of energy and power.

values for power were initially shown as energy in joules.

a constant energy value for commands of different durations seemed expected for some reason.

the maintainer is now humbly aware of this difference.