)]}'
{
  "commit": "fae71df53733f6e899986d88ea77be1e5305e2f2",
  "tree": "e7bc011815add9288f8084cf67ac4247515b0f5f",
  "parents": [
    "14addcd7c4d165ef1a74d3dd132dbc64d636d728"
  ],
  "author": {
    "name": "Di Wu",
    "email": "diwux@google.com",
    "time": "Mon Oct 19 08:23:04 2026 +0000"
  },
  "committer": {
    "name": "CrOS LUCI",
    "email": "chromeos-scoped@luci-project-accounts.iam.gserviceaccount.com",
    "time": "Mon Oct 19 23:19:02 2026 -0700"
  },
  "message": "futility: dump_kernel_config: Cut update check disk reads ~250x\n\nOn a nissa device, this makes the MiniOS version lookup that runs on\nevery update check about 250x cheaper on disk: from ~65 MB of reads\ndown to under 0.3 MB, with identical output.\n\nWhy: on every update check (roughly every 45 minutes), update_engine\nruns dump_kernel_config on the MiniOS kernel partition to get the\nMiniOS version it sends to the update server. That version sits in a\n4 KB config placed after the kernel body. To get there, the tool reads\nand throws away every byte in front of it through a 1 KB buffer: on\nnissa, ~65 MB in ~63k read() calls per check, or roughly 1-2 GB of disk\nreads per device per day.\n\nSeek past the kernel instead of reading through it. Non-seekable\ninputs such as pipes still skip by reading, and seeking past the end\nof a file is rejected as before.\n\nBUG\u003dNone\nBRANCH\u003dnone\nTEST\u003dfutility tests pass; verified on a nissa DUT.\n\nChange-Id: I420aa9f34dac0c164589f33909bb34c46d4158ed\nSigned-off-by: Di Wu \u003cdiwux@google.com\u003e\nReviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/8604326\nReviewed-by: Yu-Ping Wu \u003cyupingso@chromium.org\u003e\n",
  "tree_diff": [
    {
      "type": "modify",
      "old_id": "a3484890f0a68217590b6b2fa2a69486ad7f129c",
      "old_mode": 33188,
      "old_path": "futility/dump_kernel_config_lib.c",
      "new_id": "2adb81d07ecaca976528547cc7540bd41b705904",
      "new_mode": 33188,
      "new_path": "futility/dump_kernel_config_lib.c"
    },
    {
      "type": "modify",
      "old_id": "933d337babf496aa3aabb62a4981b534fbae3cb3",
      "old_mode": 33261,
      "old_path": "tests/run_vbutil_kernel_arg_tests.sh",
      "new_id": "91e045ad561825d45b3f61c6dceb487e6629326d",
      "new_mode": 33261,
      "new_path": "tests/run_vbutil_kernel_arg_tests.sh"
    }
  ]
}