iso-kernos
Platform support
| Platform | CPU | RAM | GPU |
|---|---|---|---|
| Linux (AMD / Intel GPU) | /proc/stat delta |
/proc/meminfo |
/sys/class/drm/cardN/device/gpu_busy_percent + sysfs VRAM nodes |
| Linux (NVIDIA GPU) | same | same | nvidia-smi fallback via popen — no NVML required |
| Windows (MinGW / MSVC) | GetSystemTimes delta |
GlobalMemoryStatusEx |
DXGI + D3DKMT (same source as Task Manager) |
Unavailable metrics return -1 and display as N/A. The program never crashes on missing hardware.
How it works
CPU — Two snapshots of idle and total CPU ticks are taken 500 ms apart. Usage is computed as:
Usage% = 100 × (1 − ΔIdle / ΔTotal)
On Linux the ticks come from /proc/stat. On Windows GetSystemTimes returns idle, kernel (which includes idle), and user times as FILETIME values; idle is subtracted from kernel to isolate busy kernel time.
RAM — A single read with no sleep. On Linux, MemTotal and MemAvailable are parsed from /proc/meminfo; used = total − available. On Windows GlobalMemoryStatusEx fills a MEMORYSTATUSEX struct that contains dwMemoryLoad, ullTotalPhys, and ullAvailPhys directly.
GPU — Linux checks /sys/class/drm/card0 through card3 for gpu_busy_percent and VRAM byte counts exposed by open-source AMD and Intel drivers. If those sysfs nodes are absent, it falls back to popen("nvidia-smi ...") and parses the CSV. On Windows, CreateDXGIFactory1 enumerates adapters; VRAM usage is queried via the IDXGIAdapter3::QueryVideoMemoryInfo vtable slot (called through a raw COM pointer to stay MinGW-compatible), and D3DKMTQueryStatistics (loaded dynamically from gdi32.dll) gives per-node engine utilisation averaged across all GPU nodes.
Polling — getCpuStats() owns the 500 ms sleep required for the CPU delta. RAM and GPU reads are instantaneous, so the overall loop cadence is naturally ≥ 500 ms with negligible CPU overhead.
Project structure
iso-kernos/
├── Monitor.hpp # Struct definitions (CpuStats, RamStats, GpuStats)
│ # and HardwareMonitor class declaration.
│ # Included on both platforms — no OS headers here.
│
├── Monitor_win.cpp # Windows-only implementation.
│ # Uses GetSystemTimes, GlobalMemoryStatusEx,
│ # DXGI + D3DKMT. All DXGI 1.4 types self-declared
│ # so MinGW and MSVC both compile without extra SDKs.
│
└── main.cpp # Entry point. Zero OS-specific code.
# Creates HardwareMonitor, calls the three stat
# methods, pretty-prints in nvidia-smi table style.
Build
Linux
g++ -std=c++17 -O2 main.cpp Monitor_linux.cpp -o iso-kernos
./iso-kernos
Windows — MinGW (g++)
g++ -std=c++17 -O2 main.cpp Monitor_win.cpp -o iso-kernos.exe -ldxgi
.\iso-kernos.exe
Windows — MSVC
cl /std:c++17 /O2 main.cpp Monitor_win.cpp /link dxgi.lib kernel32.lib
.\iso-kernos.exe