Introduction

For a general explanation, check our webpage.

jRAPL works for three Intel architectures -- Sandy Bridge, Sandy Bridge_ep (Server) and Ivy Bridge. Each architecture has different RAPL support.

• Sandy Bridge/Ivy Bridge: GPU, CPU and package support.

• Sandy Bridge_ep: DRAM, CPU and package support.

You need check which one is your CPU architecture before you use jRAPL.

For more details about RAPL, check the main reference

Pre-requisites

This library uses the kernel msr module. To use, type

sudo modprobe msr

Build

To generate the library for JNI, type

make

How to use

Everytime you need root/sudo access to run the Java code in order to access RAPL MSR.

jRAPL includes the following methods, and it needs to be declared like the following before usage:

• public native static int ProfileInit(); Initializes jRAPL. Just needs call once in the beginning.

• public native static String EnergyStatCheck(); It returns a string value, which contains the format of content like: socket1_gpu/dram_energy#socket1_cpu_energy#socket1_package_energy@socket2_gpu/dram_energy#socket2_cpu_energy#socket2_package_energy. The character '#' seperates the energy information per the socket. Character '@' seperates different sockets. If it only has one socket, there is no '@'.

• public native static void ProfileDealloc();: Free the memory initialized in ProfileInit().

The EnergyCheckUtils.java class provide a working sample on how to use jRAPL.

Known limitations

It only works for at most 2 sockets CPU.

Contributions

Want to contribute with code, documentation or bug report? That's great, check out the Issues page.

Contact

• Kenan Liu {[email protected]}