# Architecture

## Script Layers

```
bin/                    User entry points (thin dispatchers)
  audit                   → scripts/audit/
  monitor                 → scripts/monitor/
  benchmark               → scripts/benchmark/
  optimize                → scripts/optimize/

scripts/                Implementation (sourcing lib/ for shared logic)
  audit/                  System assessment
  monitor/                GPU/system monitoring + metrics logging
  benchmark/              llama-bench via toolbox containers
  optimize/               GRUB, tuned, BIOS guidance, verify, rollback

lib/                    Shared bash libraries (sourced, not executed)
  common.sh               Logging, root checks, confirm prompts, paths
  detect.sh               Hardware/config detection from sysfs + system tools
  format.sh               Color output, human_bytes, status indicators, tables

configs/                Reference configuration templates
data/                   Runtime output (gitignored)
docs/                   Documentation
```

Every script sources libs in order: `common.sh` → `detect.sh` → `format.sh`. `format.sh` depends on color variables defined in `common.sh`.

## Data Flow

```
/sys/class/drm/card1/device/   ──→  lib/detect.sh  ──→  scripts/audit/
/proc/cpuinfo, /proc/meminfo   ──→      (detect_*)  ──→  scripts/monitor/
/proc/cmdline                   ──→                  ──→  scripts/optimize/
tuned-adm, rpm, lspci          ──→                  ──→  scripts/benchmark/
                                                              │
                                                              ▼
                                                         data/
                                                           ├── audits/*.json
                                                           ├── logs/*.csv
                                                           ├── baselines/*/summary.json
                                                           └── benchmarks/*/summary.json
```

## Unified Memory Model

AMD Strix Halo shares physical RAM between CPU and GPU. Two allocation mechanisms:

| Type | Description | Configuration |
|------|-------------|---------------|
| **VRAM (dedicated)** | Permanently reserved for GPU framebuffer | BIOS setting (UMA Frame Buffer Size) |
| **GTT (dynamic)** | System RAM mapped into GPU address space on demand | Kernel boot params: `amdgpu.gttsize`, `ttm.pages_limit` |

**Optimal for LLM workloads**: Minimize VRAM (0.5 GiB), maximize GTT (~60 GiB on 64 GB system). The GPU borrows memory when needed and releases it when idle.

### Kernel Parameter Math (64 GB system)

```
Total physical RAM:     64 GiB
OS reserve:              4 GiB
Available for GTT:      60 GiB = 61440 MiB

amdgpu.gttsize = 60 * 1024         = 61440   (MiB)
ttm.pages_limit = 60 * 1024 * 256  = 15728640 (4K pages)
iommu = pt                                     (passthrough, lower latency)
```

The toolkit computes these dynamically via `recommended_gttsize_mib()` and `recommended_pages_limit()` in `lib/detect.sh`, based on detected total physical RAM (visible + VRAM).

### Sysfs Paths

| Path | Content |
|------|---------|
| `/sys/class/drm/card1/device/mem_info_vram_total` | Dedicated VRAM in bytes |
| `/sys/class/drm/card1/device/mem_info_vram_used` | VRAM currently in use |
| `/sys/class/drm/card1/device/mem_info_gtt_total` | GTT allocation in bytes |
| `/sys/class/drm/card1/device/mem_info_gtt_used` | GTT currently in use |
| `/sys/class/drm/card1/device/gpu_busy_percent` | GPU utilization 0-100 |
| `/sys/class/drm/card1/device/hwmon/hwmon*/temp1_input` | Temperature in millidegrees C |
| `/sys/class/drm/card1/device/hwmon/hwmon*/power1_average` | Power in microwatts |

Card number is auto-detected by `find_gpu_card()` (matches AMD vendor ID `0x1002`).

## JSON Output Schemas

### system-state.json (from `audit --json`)

```json
{
  "timestamp": "20260325-120000",
  "hardware": { "cpu_model": "...", "cpu_cores": 16, "cpu_threads": 32, "gpu_name": "...", "gpu_device_id": "1586", "system_ram_kb": 32609248 },
  "memory": { "vram_total_bytes": 0, "vram_used_bytes": 0, "gtt_total_bytes": 0, "gtt_used_bytes": 0, "recommended_gttsize_mib": 0, "recommended_pages_limit": 0 },
  "kernel": { "version": "...", "cmdline": "...", "param_iommu": "", "param_gttsize": "", "param_pages_limit": "" },
  "firmware": "...", "tuned_profile": "...", "rocm_version": "...",
  "vulkan": { "driver": "...", "version": "..." },
  "sensors": { "gpu_temp_mc": 0, "gpu_power_uw": 0, "gpu_busy_pct": 0 },
  "toolboxes": [], "stacks": { "ollama": "...", "lmstudio": "...", "llamacpp": "...", "opencode": "..." }
}
```

### summary.json (from benchmark runs)

```json
{
  "results": [
    { "file": "model__backend__fa1.log", "model": "...", "size": "...", "backend": "Vulkan", "test": "pp512", "tokens_per_sec": 548.18, "raw": "548.18 +/- 1.59" }
  ]
}
```

### metrics.csv (from `monitor --log`)

```
timestamp,gpu_busy_pct,vram_used_mib,gtt_used_mib,gpu_temp_c,gpu_power_w,cpu_pct,ram_used_mib
```

Sampled every 2 seconds by default. Pure bash implementation (no subshell forks per sample).