{
  "project": "gpu-pilot",
  "doc": "DESIGN.md",
  "title": "Architecture & Design",
  "oneline": "How the GPU RAPTOR kernel works and why every major decision was made.",
  "tldr": [
    "RAPTOR (round-based timetable algorithm), not GPU A* \u2014 no priority queue, every in-round update is an idempotent atomicMin, which is exactly what SIMD wants.",
    "One warp = 32 origins x one route pattern; stop-major/origin-minor tau[stop][origin] layout makes label updates one coalesced 128-byte transaction.",
    "Schedule stored twice (dep-by-stop for binary-search boarding, arr-by-trip for riding) \u2014 8 MB total, a free trade.",
    "Measured outcome: 73 ms for all 535K res-9 origins x 992 stops (target was 0.5-1 s); res-10 3.75M origins in 3.31 s.",
    "\u00a711 lists the eight external-review deltas folded in (two-mask relax, nonzero boarding slack, tiled export, honest baseline...)."
  ],
  "updated": "2026-06-10 19:09",
  "sections": [
    {
      "level": 1,
      "title": "GPU Multi-Source RAPTOR \u2014 Design"
    },
    {
      "level": 2,
      "title": "1. Problem statement"
    },
    {
      "level": 2,
      "title": "2. Data layout (struct-of-arrays)"
    },
    {
      "level": 3,
      "title": "2.1 Read-only timetable (built host-side in cudf, uploaded once)"
    },
    {
      "level": 3,
      "title": "2.2 Per-origin state (the big memory)"
    },
    {
      "level": 2,
      "title": "3. Multi-source RAPTOR on SIMD"
    },
    {
      "level": 2,
      "title": "4. Block/warp/thread granularity"
    },
    {
      "level": 2,
      "title": "5. First-mile (walk) integration"
    },
    {
      "level": 2,
      "title": "6. Last-mile / cell-to-cell"
    },
    {
      "level": 2,
      "title": "7. Multi-criteria handling"
    },
    {
      "level": 2,
      "title": "8. Validation plan"
    },
    {
      "level": 2,
      "title": "9. Risk register"
    },
    {
      "level": 2,
      "title": "10. Sprint plan"
    },
    {
      "level": 2,
      "title": "11. Review deltas accepted into the plan (2026-06-10)"
    }
  ],
  "stats": {
    "lines": 161,
    "words": 3034
  },
  "html": "https://board.certihomes.com/project-docs/gpu-pilot/DESIGN.html",
  "out_name": "DESIGN.md",
  "comments_api": "https://board.certihomes.com/api/doc-comments?project=gpu-pilot&doc=DESIGN.md"
}