iso-kernos

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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.

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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.

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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.

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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