Energy Monitoring Interface

EnergyMon provides a general C interface for energy monitoring utilities.

For details, please see the following publication and reference as appropriate:

• Connor Imes, Lars Bergstrom, and Henry Hoffmann. "A Portable Interface for Runtime Energy Monitoring". In: FSE. 2016. DOI: https://doi.org/10.1145/2950290.2983956
• You may also find an extended analysis in the Tech Report.

Applications using some libraries may need to be executed using elevated privileges.

The following instructions are for Linux systems. If you are using a different platform, change the commands accordingly.

Current EnergyMon implementation options are:

• dummy [default]
• cray-pm
• msr
• odroid
• odroid-ioctl
• osp
• osp-polling
• rapl
• shmem
• wattsup
• wattsup-libusb
• wattsup-libftdi
• zcu102

Building

This project uses CMake.

By default, all libraries will be built, with dummy as the energymon-default implementation:

mkdir _build
cd _build
cmake ..
make

To use a different default implementation, e.g., the RAPL energy monitor, specify ENERGYMON_BUILD_DEFAULT with cmake:

cmake -DENERGYMON_BUILD_DEFAULT=rapl ..

Set ENERGYMON_BUILD_DEFAULT=NONE to disable building a default implementation. Its default value is dummy.

To build only a single library, e.g., the RAPL energy monitor, specify ENERGYMON_BUILD_LIB with cmake:

cmake -DENERGYMON_BUILD_LIB=rapl ..

Set ENERGYMON_BUILD_LIB=NONE to only build the default implementation (if set). Set back to its default value of ALL to build all libraries.

To build shared objects / dynamically linked libraries instead of static libraries, set BUILD_SHARED_LIBS with cmake:

cmake .. -DBUILD_SHARED_LIBS=ON

For an optimized build, set CMAKE_BUILD_TYPE when with cmake, e.g., one of:

cmake .. -DCMAKE_BUILD_TYPE=Release
cmake .. -DCMAKE_BUILD_TYPE=RelWithDebInfo

Of course, you can specify multiple options, e.g.:

cmake .. -DENERGYMON_BUILD_LIB=NONE -DENERGYMON_BUILD_DEFAULT=rapl -DBUILD_SHARED_LIBS=ON -DCMAKE_BUILD_TYPE=Release

Other Build Options

Boolean options:

• ENERGYMON_BUILD_SHMEM_PROVIDERS - enable/disable building shared memory providers (True by default)
• ENERGYMON_BUILD_UTILITIES - enable/disable building utility applications (True by default, dependent on building energymon-default)
• ENERGYMON_BUILD_TESTS - enable/disable building test code (True by default, dependent on building energymon-default)
• ENERGYMON_BUILD_EXAMPLES - enable/disable building examples (True by default)

Installing

To install libraries, headers, and binaries, run with proper privileges:

make install

On Linux, the installation usually places libraries in /usr/local/lib, header files in /usr/local/include/energymon, and binary files in /usr/local/bin.

Uninstalling

To remove files installed to the system, run with proper privileges:

make uninstall

Linking

The best approach for linking with any EnergyMon library is to use pkg-config. This is especially useful if building and linking to static libraries to ensure that you link with transitive dependencies.

For example, to link with energymon-default, whose implementation is not always known in advance:

pkg-config energymon-default --libs --static

If your project is using CMake, you can use pkg-config to find the library and necessary flags. For example, to find energymon-default, its headers, and to link with it and any transitive dependencies:

find_package(PkgConfig REQUIRED)
pkg_check_modules(ENERGYMON REQUIRED energymon-default)
include_directories(${ENERGYMON_INCLUDE_DIRS})

add_executable(hello_world hello_world.c)
target_link_libraries(hello_world -L${ENERGYMON_LIBDIR} ${ENERGYMON_LIBRARIES})

Usage

To use an EnergyMon implementation, you must first populate the struct by calling the getter function, then initialize it. Don't forget to cleanup the instance once you're finished with it. See energymon.h and energymon-default.h for more detailed function descriptions.

  energymon em;
  uint64_t start_uj, end_uj;

  // get the energymon instance and initialize
  energymon_get_default(&em);
  em.finit(&em);

  // profile application function
  start_uj = em.fread(&em);
  do_work();
  end_uj = em.fread(&em);
  printf("Total energy for do_work() in microjoules: %"PRIu64"\n", end_uj - start_uj);

  // destroy the instance
  em.ffinish(&em);

Tools

This project includes a handful of applications.

Utilities

All of the following are linked with energymon-default:

• energymon-cmd-profile: Prints out time, energy, and power statistics for the execution of a given shell command.
• energymon-power-poller: Prints average power values at the requested interval for the previous interval period.
• energymon-file-provider: Writes energy data to a file (overwrites previous values).
• energymon-idle-power: Prints the average power over the given interval (meant to run in isolation and measure idle power consumption).
• energymon-info: Prints information about the implementation.
• energymon-overhead: Prints the latency overhead in nanoseconds of the functions finit, fread, and ffinish.

Shared Memory Providers

Shared memory providers allow exposing energy data to one or more unprivileged applications for sources that require elevated privileges and/or exclusive access. The providers may need to run with elevated privileges, but other applications can attach to their shared memory and read energy data using the shmem EnergyMon implementation.

• energymon-osp-polling-shmem-provider
• energymon-wattsup-shmem-provider

Project Source

Find this and related project sources at the energymon organization on GitHub.
This project originates at: https://github.com/energymon/energymon

Bug reports and pull requests for new implementations, bug fixes, and enhancements are welcome.