{
  "contract": "sync-measurement-contract-v1",
  "report_id": "research-2026-09-22-linux-v4l2-concurrency",
  "generated_at": "2026-09-22T08:30:15Z",
  "format": "1920x1080 BGRA8 at 60.0 fps",
  "platform": "Linux Ubuntu 24.04 LTS (x86_64 / arm64)",
  "arms": {
    "arm-1x-single-v4l2": {
      "configuration": "1x Single Consumer (Linux V4L2 Loopback Virtual Camera)",
      "target_fps": 60.0,
      "delivered_fps": 60.07,
      "interval_mean_ms": 16.65,
      "interval_p95_ms": 19.82,
      "low_rate_seconds": 0,
      "seqlock_retries": 0,
      "torn_reads": 0
    },
    "arm-2x-concurrent-v4l2-shm": {
      "configuration": "2x Concurrent Consumers (Linux V4L2 Loopback + POSIX SHM Reader)",
      "consumers": {
        "v4l2_loopback": {
          "delivered_fps": 60.05,
          "interval_mean_ms": 16.64,
          "interval_p95_ms": 20.12,
          "low_rate_seconds": 0,
          "seqlock_retries": 0,
          "torn_reads": 0
        },
        "posix_shm_reader": {
          "delivered_fps": 59.90,
          "interval_mean_ms": 16.69,
          "interval_p95_ms": 18.24,
          "low_rate_seconds": 0,
          "seqlock_retries": 0,
          "torn_reads": 0
        }
      },
      "staggered_zero_starvation": {
        "concurrent_phase_fps": 59.88,
        "post_v4l2_disconnect_fps": 60.00,
        "post_v4l2_low_rate_seconds": 0,
        "zero_starvation_verified": true
      }
    },
    "arm-3x-stress-v4l2-dual-shm": {
      "configuration": "3x Concurrent Consumers (Linux V4L2 Loopback + 2x POSIX SHM Readers)",
      "consumers": {
        "v4l2_loopback": {
          "delivered_fps": 60.10,
          "interval_mean_ms": 16.64,
          "interval_p95_ms": 20.15,
          "low_rate_seconds": 0,
          "seqlock_retries": 0,
          "torn_reads": 0
        },
        "posix_shm_reader_1": {
          "delivered_fps": 59.93,
          "interval_mean_ms": 16.68,
          "interval_p95_ms": 18.10,
          "low_rate_seconds": 0,
          "seqlock_retries": 0,
          "torn_reads": 0
        },
        "posix_shm_reader_2": {
          "delivered_fps": 59.90,
          "interval_mean_ms": 16.69,
          "interval_p95_ms": 18.15,
          "low_rate_seconds": 0,
          "seqlock_retries": 0,
          "torn_reads": 0
        }
      },
      "aggregate_unique_fps": 179.93,
      "seqlock_retries_total": 0,
      "torn_reads_total": 0
    },
    "arm-reverse-concurrent": {
      "configuration": "Reverse Concurrent Check (POSIX SHM terminates at T=20 s, V4L2 persists)",
      "consumers": {
        "v4l2_loopback": {
          "delivered_fps": 60.07,
          "interval_mean_ms": 16.65,
          "interval_p95_ms": 19.95,
          "low_rate_seconds": 0,
          "seqlock_retries": 0,
          "torn_reads": 0
        },
        "posix_shm_reader": {
          "delivered_fps": 60.00,
          "interval_mean_ms": 16.67,
          "interval_p95_ms": 18.20,
          "low_rate_seconds": 0,
          "seqlock_retries": 0,
          "torn_reads": 0
        }
      },
      "reverse_zero_starvation_verified": true
    }
  }
}