)]}'
{
  "commit": "3da367c3e5fca71d4e778fa565d9b098d5518f4a",
  "tree": "915dff1989bdffaed157b56f724631b5d8f2d328",
  "parents": [
    "3fa36acbced23c563345de3179dfe1775f15be5e"
  ],
  "author": {
    "name": "Shaohua Li",
    "email": "shaohua.li@intel.com",
    "time": "Mon Oct 31 17:07:03 2011 -0700"
  },
  "committer": {
    "name": "Linus Torvalds",
    "email": "torvalds@linux-foundation.org",
    "time": "Mon Oct 31 17:30:45 2011 -0700"
  },
  "message": "vmscan: add block plug for page reclaim\n\nper-task block plug can reduce block queue lock contention and increase\nrequest merge.  Currently page reclaim doesn\u0027t support it.  I originally\nthought page reclaim doesn\u0027t need it, because kswapd thread count is\nlimited and file cache write is done at flusher mostly.\n\nWhen I test a workload with heavy swap in a 4-node machine, each CPU is\ndoing direct page reclaim and swap.  This causes block queue lock\ncontention.  In my test, without below patch, the CPU utilization is about\n2% ~ 7%.  With the patch, the CPU utilization is about 1% ~ 3%.  Disk\nthroughput isn\u0027t changed.  This should improve normal kswapd write and\nfile cache write too (increase request merge for example), but might not\nbe so obvious as I explain above.\n\nSigned-off-by: Shaohua Li \u003cshaohua.li@intel.com\u003e\nCc: Jens Axboe \u003caxboe@kernel.dk\u003e\nCc: Minchan Kim \u003cminchan.kim@gmail.com\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n",
  "tree_diff": [
    {
      "type": "modify",
      "old_id": "b68a9342d5a3459fc4ea2d9ec674b142b1311620",
      "old_mode": 33188,
      "old_path": "mm/vmscan.c",
      "new_id": "b1520b077858aeda1485bf0a29fadb2724e89494",
      "new_mode": 33188,
      "new_path": "mm/vmscan.c"
    }
  ]
}