cppjoules-windows

A Windows-only simplification of CPPJoules by rishalab — stripped down to 2 files, no CMake, no dependencies, plug-and-play with Visual Studio.

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What This Is

CPPJoules is a cross-platform C++ energy measurement library. This fork simplifies it for Windows developers who just want to measure CPU energy consumption without dealing with Linux RAPL paths, NVML, or a CMake build.

Drop cppJoules.h and cppJoules.cpp into your project and you're done.

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Requirements

Requirement	Notes
Windows 11 (x64)	x86 not supported — Power Gadget is 64-bit only
Intel Power Gadget 3.6	Installs EnergyLib64.dll into System32
Visual Studio 2019 or later	C++17 or later

Intel Power Gadget 3.6 installer is available in the original CPPJoules repo.

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What Was Changed from the Original

Change	Detail
7 files → 2 files	EnergyState, CPPJoulesException, RAPLDevice, EnergyTracker merged into cppJoules.h / cppJoules.cpp
Linux code removed	All /sys/class/powercap/ RAPL file reads, unistd.h, filesystem for Linux removed
macOS code removed	Apple framework path and dlfcn.h removed
NVML/Nvidia removed	nvidia_devices.h/.cpp and nvml.h dependency removed entirely
LoadLibrary → LoadLibraryA	Fixes Unicode mismatch in MSVC with char* path
wchar_t narrowing fixed	Replaced std::string(ws.begin(), ws.end()) with WideCharToMultiByte — fixes C4244 warning
Missing destructors added	~RAPLDevice() calls FreeLibrary(), ~EnergyTracker() deletes RAPLDevice* — fixes resource leaks
initialized typo fixed	Original had #ifdef _W64 (wrong) instead of _WIN64 — flag was never set
EXPOSE_DLL removed	Pointless in a plain .exe, caused C4251 noise on all STL members
EnergyState → value semantics	Changed from vector<EnergyState*> with raw new to vector<EnergyState>

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Usage

1. Add files to your project

Copy cppJoules.h and cppJoules.cpp into your project folder. In Visual Studio: Add → Existing Item for both files.

2. Set platform to x64

Toolbar → change platform dropdown from x86 to x64.

3. Set C++ standard to C++17

Project Properties → C/C++ → Language → C++ Language Standard → ISO C++17

4. Run as Administrator

Intel Power Gadget requires elevated access to read MSR counters. Without it, all readings will be 0.

5. Include and use

#include "cppJoules.h"

int main()
{
    EnergyTracker tracker;

    tracker.start();
    // your code here
    tracker.stop();

    tracker.calculate_energy();
    tracker.print_energy();           // prints mJ per domain to stdout
    tracker.save_csv("results.csv");  // optional

    return 0;
}

Example output

Duration (s): 1.84
DRAM-0      : 4 mJ
IA-0        : 612 mJ
Processor-0 : 987 mJ

Energy domains depend on your CPU. Common ones:

• Processor-0 — total package power
• IA-0 — CPU cores only
• DRAM-0 — memory controller (not available on all laptop CPUs)
• GT-0 — integrated GPU

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API Reference

EnergyTracker tracker;       // loads EnergyLib64.dll, discovers power domains

tracker.start();             // records start timestamp + energy snapshot
tracker.stop();              // records stop timestamp + energy snapshot
tracker.calculate_energy();  // computes delta, resets state for reuse
tracker.print_energy();      // prints Duration + mJ per domain to stdout
tracker.save_csv("out.csv"); // writes results to CSV file

calculate_energy() resets the tracker state to UNINITIALIZED, so start() can be called again for the next measurement.

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Troubleshooting

Symptom	Cause	Fix
Could not load EnergyLib64.dll	Power Gadget not installed	Install Intel Power Gadget 3.6
All readings are 0 mJ	Not running as Administrator	Re-run with admin rights
Build error on cppJoules.h	Wrong include path	Confirm cppJoules.h is in the same folder or add its path to Additional Include Directories
LNK2019 unresolved external	cppJoules.cpp not in project	Add via Add → Existing Item

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License

MIT — see LICENSE. Original work by rishalab.