)]}'
{
  "commit": "f86296317434b21585e229f6c49a33cb9ebab4d3",
  "tree": "d4fb05d4aee1a8e373ec053e7316dc9847b2c417",
  "parents": [
    "1a8670a29b5277cbe601f74ab63d2c5211fb3005"
  ],
  "author": {
    "name": "Wu Fengguang",
    "email": "fengguang.wu@intel.com",
    "time": "Mon Sep 21 17:03:11 2009 -0700"
  },
  "committer": {
    "name": "Linus Torvalds",
    "email": "torvalds@linux-foundation.org",
    "time": "Tue Sep 22 07:17:39 2009 -0700"
  },
  "message": "mm: do batched scans for mem_cgroup\n\nFor mem_cgroup, shrink_zone() may call shrink_list() with nr_to_scan\u003d1, in\nwhich case shrink_list() _still_ calls isolate_pages() with the much\nlarger SWAP_CLUSTER_MAX.  It effectively scales up the inactive list scan\nrate by up to 32 times.\n\nFor example, with 16k inactive pages and DEF_PRIORITY\u003d12, (16k \u003e\u003e 12)\u003d4.\nSo when shrink_zone() expects to scan 4 pages in the active/inactive list,\nthe active list will be scanned 4 pages, while the inactive list will be\n(over) scanned SWAP_CLUSTER_MAX\u003d32 pages in effect.  And that could break\nthe balance between the two lists.\n\nIt can further impact the scan of anon active list, due to the anon\nactive/inactive ratio rebalance logic in balance_pgdat()/shrink_zone():\n\ninactive anon list over scanned \u003d\u003e inactive_anon_is_low() \u003d\u003d TRUE\n                                \u003d\u003e shrink_active_list()\n                                \u003d\u003e active anon list over scanned\n\nSo the end result may be\n\n- anon inactive  \u003d\u003e over scanned\n- anon active    \u003d\u003e over scanned (maybe not as much)\n- file inactive  \u003d\u003e over scanned\n- file active    \u003d\u003e under scanned (relatively)\n\nThe accesses to nr_saved_scan are not lock protected and so not 100%\naccurate, however we can tolerate small errors and the resulted small\nimbalanced scan rates between zones.\n\nCc: Rik van Riel \u003criel@redhat.com\u003e\nReviewed-by: KOSAKI Motohiro \u003ckosaki.motohiro@jp.fujitsu.com\u003e\nAcked-by: Balbir Singh \u003cbalbir@linux.vnet.ibm.com\u003e\nReviewed-by: Minchan Kim \u003cminchan.kim@gmail.com\u003e\nSigned-off-by: KAMEZAWA Hiroyuki \u003ckamezawa.hiroyu@jp.fujitsu.com\u003e\nSigned-off-by: Wu Fengguang \u003cfengguang.wu@intel.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": "9c50309b30a1483b7fbca1611814421d231e2e08",
      "old_mode": 33188,
      "old_path": "include/linux/mmzone.h",
      "new_id": "c188ea624c7426fb8f602712d9e8bcb2bdc0b1bf",
      "new_mode": 33188,
      "new_path": "include/linux/mmzone.h"
    },
    {
      "type": "modify",
      "old_id": "770f011e1c12486a2d680e63aeb32324da671f4f",
      "old_mode": 33188,
      "old_path": "mm/page_alloc.c",
      "new_id": "84d9da1e8f4c34532206ccea3604981707e440ee",
      "new_mode": 33188,
      "new_path": "mm/page_alloc.c"
    },
    {
      "type": "modify",
      "old_id": "5432c230c4cb0d68357e2bbaa18bb21ec48d5831",
      "old_mode": 33188,
      "old_path": "mm/vmscan.c",
      "new_id": "0e7f5e4a22d7c2f6e9c7bf283d50bdc3c1ad8d73",
      "new_mode": 33188,
      "new_path": "mm/vmscan.c"
    }
  ]
}