RefRAPL

A Reference Implementation of C code to read the values of the RAPL MSRs for running energy use on linux. Includes a custom kernel module for low overhead. Built on a nixos system, userspace should be portable to other linux distros.

refRAPL.c

A pure c program that takes a file name and a program to run.

NOTE: Must be run as sudo to use the msr kernal moduel

ex

sudo ./build/useModRefRapl "python testPrograms/badfib.py 30" a

Will run a test and name the output files starting with a

build

make

Data format

[test_name].data

A running append of the 100 samples of the rapl registers with a timestamp collected every milisecond. Saved in raw binary format. The struct looks like

struct raplMeasurement {
    u_int64_t ms_timestamp;
    u_int64_t pkg, pp0, pp1, dram;
};

[test_name]_pts.data

4 timestamps over the execustion window. All 4 are u_int64_t u_int64_t t1,t2,t3,t4;

useModRefRAPL.c

Run the same way as refRAPL.c but uses the /proc/rapl_ref_dump interface for low overhead. Can be run with normal user privs but the module must already be loaded

ex

./build/useModRefRapl "python testPrograms/badfib.py 30" a

Will run a test and name the output files starting with a

build

make

Data format

[test_name].data

A running append of the 128 samples of the rapl buffer collected every 0.1 seconds in the kernel. Saved in raw binary format. The buffer is a ring and there should be up to 48 redundent entries per 2 second dump. The struct looks like

struct raplMeasurement {
    u_int64_t ms_timestamp;
    u_int64_t pkg, pp0, pp1, dram;
};

[test_name]_pts.data

4 timestamps over the execustion window. All 4 are u_int64_t u_int64_t t1,t2,t3,t4;

dataToCSV.c

Takes a testname and makes a testname_output.csv from testname.data and testname_pts.data

ex

For a test in the data folder named a

./build/dataToCsv data/a

NOTE: If the files were made with sudo (for example becuse you used sudo refRAPL.c) you may get and error unless you use sudo again.

build

make

testPrograms

badfib.py: a bad recursive fib python program to test cpu usage

kernMod/src/rapl_ref_mod.c

A custom out of tree kernel module that exposes 2 proc devices. Keeps 2048 samples in a ring buffer in kernel space

/proc/rapl_ref

outputs a format string converted version of the current measurement buffer, good for debugging

/proc/rapl_ref_dump

outputs a binary dump of the current measurement buffer

build

Built on a nixos system using nix-build in the kenrMod directory. The shell.nix ensures you have the needed dependecies and provides a qemu setup for testing

cd kernMod
nix-build