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Energy Profiling for Erlang and Elixir

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power_rapl_erl is a tool to provide the profiling energy consumption for Erlang and Elixirfor the whole CPU. power_rapl_erl use Inte's RAPL (Running Average Power Limit) interface to indicate the amount of energy consumed.

How to build power_rapl_erl

To build power_rapl_erl you just need compile the file, indicating where is our erlang/usr/include path:

   $  gcc -fPIC -shared -o rapl_erl.so rapl_erl.c -I /*/erlang/usr/include/

Compile the rapl_nif and rapl_erl files too.

   $ erlc rapl_nif.erl rapl_erl.erl

Remeber to change the permission to access the /dev/cpu/*/msr file, or run your code as root.

IMPORTANT: You need to make sure that the “msr” driver is loaded before you can start using power_rapl_erl. You can do that checking for following directories:

        $ ls /dev/cpu/0/msr

If this directory does not exist. You can load the “msr” module by the following command:

        $ sudo modprobe msr

How to use power_rapl_erl

Run in Erlang:

   1> rapl_erl:start_energy_profiling(fibonacci, fib, [4]).
    Result: 3
       MODULE      |    FUNCTION   |    ENERGY BEFORE      |     ENERGY AFTER      |     ENERGY CONSUMED
    fibonacci      |         fib   |     50267.433258      |     50267.451721      |            0.018463

Run in Elixir:

   iex(1)> :rapl_erl.start_energy_profiling(Fibonacci, :fib, [4])
    Result: 5
        MODULE      |    FUNCTION   |    ENERGY BEFORE      |     ENERGY AFTER      |     ENERGY CONSUMED
    Elixir.Fib      |         fib   |     54245.303635      |     54245.310242      |            0.006607