)]}'
{
  "commit": "55c022bbddb2c056b5dff1bd1b1758d31b6d64c9",
  "tree": "fdd3aa29a1407bbd19b8efe47b2538544da85a70",
  "parents": [
    "719c0c590609809365c6f3da2f923cd84dc99113"
  ],
  "author": {
    "name": "Shaohua Li",
    "email": "shaohua.li@intel.com",
    "time": "Fri Jul 08 08:19:20 2011 +0200"
  },
  "committer": {
    "name": "Jens Axboe",
    "email": "jaxboe@fusionio.com",
    "time": "Fri Jul 08 08:19:20 2011 +0200"
  },
  "message": "block: avoid building too big plug list\n\nWhen I test fio script with big I/O depth, I found the total throughput drops\ncompared to some relative small I/O depth. The reason is the thread accumulates\nbig requests in its plug list and causes some delays (surely this depends\non CPU speed).\nI thought we\u0027d better have a threshold for requests. When a threshold reaches,\nthis means there is no request merge and queue lock contention isn\u0027t severe\nwhen pushing per-task requests to queue, so the main advantages of blk plug\ndon\u0027t exist. We can force a plug list flush in this case.\nWith this, my test throughput actually increases and almost equals to small\nI/O depth. Another side effect is irq off time decreases in blk_flush_plug_list()\nfor big I/O depth.\nThe BLK_MAX_REQUEST_COUNT is choosen arbitarily, but 16 is efficiently to\nreduce lock contention to me. But I\u0027m open here, 32 is ok in my test too.\n\nSigned-off-by: Shaohua Li \u003cshaohua.li@intel.com\u003e\nSigned-off-by: Jens Axboe \u003cjaxboe@fusionio.com\u003e\n",
  "tree_diff": [
    {
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      "old_mode": 33188,
      "old_path": "block/blk-core.c",
      "new_id": "a564852920626a7984935bbf21aba5c5722e3908",
      "new_mode": 33188,
      "new_path": "block/blk-core.c"
    },
    {
      "type": "modify",
      "old_id": "36f2e2b99ae3879bbc201ab3effd9cec7f0e2e21",
      "old_mode": 33188,
      "old_path": "include/linux/blkdev.h",
      "new_id": "92edb9601242d1c8252056d5820925fd2d2821f1",
      "new_mode": 33188,
      "new_path": "include/linux/blkdev.h"
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}