)]}'
{
  "log": [
    {
      "commit": "d527caf22e48480b102c7c6ee5b9ba12170148f7",
      "tree": "7d53a2c430f8c020b6fa8390396dd2d1ce480b9a",
      "parents": [
        "89699605fe7cfd8611900346f61cb6cbf179b10a"
      ],
      "author": {
        "name": "Andrea Arcangeli",
        "email": "aarcange@redhat.com",
        "time": "Tue Mar 22 16:30:38 2011 -0700"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Tue Mar 22 17:44:00 2011 -0700"
      },
      "message": "mm: compaction: prevent kswapd compacting memory to reduce CPU usage\n\nThis patch reverts 5a03b051 (\"thp: use compaction in kswapd for GFP_ATOMIC\norder \u003e 0\") due to reports stating that kswapd CPU usage was higher and\nIRQs were being disabled more frequently.  This was reported at\nhttp://www.spinics.net/linux/fedora/alsa-user/msg09885.html.\n\nWithout this patch applied, CPU usage by kswapd hovers around the 20% mark\naccording to the tester (Arthur Marsh:\nhttp://www.spinics.net/linux/fedora/alsa-user/msg09899.html).  With this\npatch applied, it\u0027s around 2%.\n\nThe problem is not related to THP which specifies __GFP_NO_KSWAPD but is\ntriggered by high-order allocations hitting the low watermark for their\norder and waking kswapd on kernels with CONFIG_COMPACTION set.  The most\ncommon trigger for this is network cards configured for jumbo frames but\nit\u0027s also possible it\u0027ll be triggered by fork-heavy workloads (order-1)\nand some wireless cards which depend on order-1 allocations.\n\nThe symptoms for the user will be high CPU usage by kswapd in low-memory\nsituations which could be confused with another writeback problem.  While\na patch like 5a03b051 may be reintroduced in the future, this patch plays\nit safe for now and reverts it.\n\n[mel@csn.ul.ie: Beefed up the changelog]\nSigned-off-by: Andrea Arcangeli \u003caarcange@redhat.com\u003e\nSigned-off-by: Mel Gorman \u003cmel@csn.ul.ie\u003e\nReported-by: Arthur Marsh \u003carthur.marsh@internode.on.net\u003e\nTested-by: Arthur Marsh \u003carthur.marsh@internode.on.net\u003e\nCc: \u003cstable@kernel.org\u003e\t\t[2.6.38.1]\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "5a03b051ed87e72b959f32a86054e1142ac4cf55",
      "tree": "31f0e8efb86d48b0292f8a7ea4bd9cf7c930a0ab",
      "parents": [
        "878aee7d6b5504e01b9caffce080e792b6b8d090"
      ],
      "author": {
        "name": "Andrea Arcangeli",
        "email": "aarcange@redhat.com",
        "time": "Thu Jan 13 15:47:11 2011 -0800"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Thu Jan 13 17:32:46 2011 -0800"
      },
      "message": "thp: use compaction in kswapd for GFP_ATOMIC order \u003e 0\n\nThis takes advantage of memory compaction to properly generate pages of\norder \u003e 0 if regular page reclaim fails and priority level becomes more\nsevere and we don\u0027t reach the proper watermarks.\n\nSigned-off-by: Andrea Arcangeli \u003caarcange@redhat.com\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "77f1fe6b08b13a87391549c8a820ddc817b6f50e",
      "tree": "720865bd0994da3787b6f37d33b2ee4c26a2de6c",
      "parents": [
        "3e7d344970673c5334cf7b5bb27c8c0942b06126"
      ],
      "author": {
        "name": "Mel Gorman",
        "email": "mel@csn.ul.ie",
        "time": "Thu Jan 13 15:45:57 2011 -0800"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Thu Jan 13 17:32:34 2011 -0800"
      },
      "message": "mm: migration: allow migration to operate asynchronously and avoid synchronous compaction in the faster path\n\nMigration synchronously waits for writeback if the initial passes fails.\nCallers of memory compaction do not necessarily want this behaviour if the\ncaller is latency sensitive or expects that synchronous migration is not\ngoing to have a significantly better success rate.\n\nThis patch adds a sync parameter to migrate_pages() allowing the caller to\nindicate if wait_on_page_writeback() is allowed within migration or not.\nFor reclaim/compaction, try_to_compact_pages() is first called\nasynchronously, direct reclaim runs and then try_to_compact_pages() is\ncalled synchronously as there is a greater expectation that it\u0027ll succeed.\n\n[akpm@linux-foundation.org: build/merge fix]\nSigned-off-by: Mel Gorman \u003cmel@csn.ul.ie\u003e\nCc: Andrea Arcangeli \u003caarcange@redhat.com\u003e\nCc: KOSAKI Motohiro \u003ckosaki.motohiro@jp.fujitsu.com\u003e\nCc: Rik van Riel \u003criel@redhat.com\u003e\nAcked-by: Johannes Weiner \u003channes@cmpxchg.org\u003e\nCc: Andy Whitcroft \u003capw@shadowen.org\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "3e7d344970673c5334cf7b5bb27c8c0942b06126",
      "tree": "832ecb4da5fd27efa5a503df5b96bfdee2a52ffd",
      "parents": [
        "ee64fc9354e515a79c7232cfde65c88ec627308b"
      ],
      "author": {
        "name": "Mel Gorman",
        "email": "mel@csn.ul.ie",
        "time": "Thu Jan 13 15:45:56 2011 -0800"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Thu Jan 13 17:32:33 2011 -0800"
      },
      "message": "mm: vmscan: reclaim order-0 and use compaction instead of lumpy reclaim\n\nLumpy reclaim is disruptive.  It reclaims a large number of pages and\nignores the age of the pages it reclaims.  This can incur significant\nstalls and potentially increase the number of major faults.\n\nCompaction has reached the point where it is considered reasonably stable\n(meaning it has passed a lot of testing) and is a potential candidate for\ndisplacing lumpy reclaim.  This patch introduces an alternative to lumpy\nreclaim whe compaction is available called reclaim/compaction.  The basic\noperation is very simple - instead of selecting a contiguous range of\npages to reclaim, a number of order-0 pages are reclaimed and then\ncompaction is later by either kswapd (compact_zone_order()) or direct\ncompaction (__alloc_pages_direct_compact()).\n\n[akpm@linux-foundation.org: fix build]\n[akpm@linux-foundation.org: use conventional task_struct naming]\nSigned-off-by: Mel Gorman \u003cmel@csn.ul.ie\u003e\nCc: Andrea Arcangeli \u003caarcange@redhat.com\u003e\nCc: KOSAKI Motohiro \u003ckosaki.motohiro@jp.fujitsu.com\u003e\nCc: Rik van Riel \u003criel@redhat.com\u003e\nAcked-by: Johannes Weiner \u003channes@cmpxchg.org\u003e\nCc: Andy Whitcroft \u003capw@shadowen.org\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "4f92e2586b43a2402e116055d4edda704f911b5b",
      "tree": "6a765ebeba951c02a7878bcea52a4769ad2e45c2",
      "parents": [
        "5e7719058079a1423ccce56148b0aaa56b2df821"
      ],
      "author": {
        "name": "Mel Gorman",
        "email": "mel@csn.ul.ie",
        "time": "Mon May 24 14:32:32 2010 -0700"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Tue May 25 08:07:00 2010 -0700"
      },
      "message": "mm: compaction: defer compaction using an exponential backoff when compaction fails\n\nThe fragmentation index may indicate that a failure is due to external\nfragmentation but after a compaction run completes, it is still possible\nfor an allocation to fail.  There are two obvious reasons as to why\n\n  o Page migration cannot move all pages so fragmentation remains\n  o A suitable page may exist but watermarks are not met\n\nIn the event of compaction followed by an allocation failure, this patch\ndefers further compaction in the zone (1 \u003c\u003c compact_defer_shift) times.\nIf the next compaction attempt also fails, compact_defer_shift is\nincreased up to a maximum of 6.  If compaction succeeds, the defer\ncounters are reset again.\n\nThe zone that is deferred is the first zone in the zonelist - i.e.  the\npreferred zone.  To defer compaction in the other zones, the information\nwould need to be stored in the zonelist or implemented similar to the\nzonelist_cache.  This would impact the fast-paths and is not justified at\nthis time.\n\nSigned-off-by: Mel Gorman \u003cmel@csn.ul.ie\u003e\nCc: Rik van Riel \u003criel@redhat.com\u003e\nCc: Minchan Kim \u003cminchan.kim@gmail.com\u003e\nCc: KOSAKI Motohiro \u003ckosaki.motohiro@jp.fujitsu.com\u003e\nCc: Christoph Lameter \u003ccl@linux-foundation.org\u003e\nCc: KAMEZAWA Hiroyuki \u003ckamezawa.hiroyu@jp.fujitsu.com\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "5e7719058079a1423ccce56148b0aaa56b2df821",
      "tree": "3666cb3d5540dcaa3d8e7df8c293a0ad603a181c",
      "parents": [
        "56de7263fcf3eb10c8dcdf8d59a9cec831795f3f"
      ],
      "author": {
        "name": "Mel Gorman",
        "email": "mel@csn.ul.ie",
        "time": "Mon May 24 14:32:31 2010 -0700"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Tue May 25 08:06:59 2010 -0700"
      },
      "message": "mm: compaction: add a tunable that decides when memory should be compacted and when it should be reclaimed\n\nThe kernel applies some heuristics when deciding if memory should be\ncompacted or reclaimed to satisfy a high-order allocation.  One of these\nis based on the fragmentation.  If the index is below 500, memory will not\nbe compacted.  This choice is arbitrary and not based on data.  To help\noptimise the system and set a sensible default for this value, this patch\nadds a sysctl extfrag_threshold.  The kernel will only compact memory if\nthe fragmentation index is above the extfrag_threshold.\n\n[randy.dunlap@oracle.com: Fix build errors when proc fs is not configured]\nSigned-off-by: Mel Gorman \u003cmel@csn.ul.ie\u003e\nSigned-off-by: Randy Dunlap \u003crandy.dunlap@oracle.com\u003e\nCc: Rik van Riel \u003criel@redhat.com\u003e\nCc: Minchan Kim \u003cminchan.kim@gmail.com\u003e\nCc: KOSAKI Motohiro \u003ckosaki.motohiro@jp.fujitsu.com\u003e\nCc: Christoph Lameter \u003ccl@linux-foundation.org\u003e\nCc: KAMEZAWA Hiroyuki \u003ckamezawa.hiroyu@jp.fujitsu.com\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "56de7263fcf3eb10c8dcdf8d59a9cec831795f3f",
      "tree": "164637c0b678e20adfdcec4129563d9234faf405",
      "parents": [
        "ed4a6d7f0676db50b5023cc01f6cda82a2f2a307"
      ],
      "author": {
        "name": "Mel Gorman",
        "email": "mel@csn.ul.ie",
        "time": "Mon May 24 14:32:30 2010 -0700"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Tue May 25 08:06:59 2010 -0700"
      },
      "message": "mm: compaction: direct compact when a high-order allocation fails\n\nOrdinarily when a high-order allocation fails, direct reclaim is entered\nto free pages to satisfy the allocation.  With this patch, it is\ndetermined if an allocation failed due to external fragmentation instead\nof low memory and if so, the calling process will compact until a suitable\npage is freed.  Compaction by moving pages in memory is considerably\ncheaper than paging out to disk and works where there are locked pages or\nno swap.  If compaction fails to free a page of a suitable size, then\nreclaim will still occur.\n\nDirect compaction returns as soon as possible.  As each block is\ncompacted, it is checked if a suitable page has been freed and if so, it\nreturns.\n\n[akpm@linux-foundation.org: Fix build errors]\n[aarcange@redhat.com: fix count_vm_event preempt in memory compaction direct reclaim]\nSigned-off-by: Mel Gorman \u003cmel@csn.ul.ie\u003e\nAcked-by: Rik van Riel \u003criel@redhat.com\u003e\nReviewed-by: Minchan Kim \u003cminchan.kim@gmail.com\u003e\nCc: KOSAKI Motohiro \u003ckosaki.motohiro@jp.fujitsu.com\u003e\nCc: Christoph Lameter \u003ccl@linux-foundation.org\u003e\nCc: KAMEZAWA Hiroyuki \u003ckamezawa.hiroyu@jp.fujitsu.com\u003e\nSigned-off-by: Andrea Arcangeli \u003caarcange@redhat.com\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "ed4a6d7f0676db50b5023cc01f6cda82a2f2a307",
      "tree": "6496343ba964e105cf30f8703714471f22edc806",
      "parents": [
        "76ab0f530e4a01d4dc20cdc1d5e87753c579dc18"
      ],
      "author": {
        "name": "Mel Gorman",
        "email": "mel@csn.ul.ie",
        "time": "Mon May 24 14:32:29 2010 -0700"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Tue May 25 08:06:59 2010 -0700"
      },
      "message": "mm: compaction: add /sys trigger for per-node memory compaction\n\nAdd a per-node sysfs file called compact.  When the file is written to,\neach zone in that node is compacted.  The intention that this would be\nused by something like a job scheduler in a batch system before a job\nstarts so that the job can allocate the maximum number of hugepages\nwithout significant start-up cost.\n\nSigned-off-by: Mel Gorman \u003cmel@csn.ul.ie\u003e\nAcked-by: Rik van Riel \u003criel@redhat.com\u003e\nReviewed-by: KOSAKI Motohiro \u003ckosaki.motohiro@jp.fujitsu.com\u003e\nReviewed-by: Christoph Lameter \u003ccl@linux-foundation.org\u003e\nReviewed-by: Minchan Kim \u003cminchan.kim@gmail.com\u003e\nReviewed-by: KAMEZAWA Hiroyuki \u003ckamezawa.hiroyu@jp.fujitsu.com\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "76ab0f530e4a01d4dc20cdc1d5e87753c579dc18",
      "tree": "8e1566df85e02f67876685c36d217fec4845f79f",
      "parents": [
        "748446bb6b5a9390b546af38ec899c868a9dbcf0"
      ],
      "author": {
        "name": "Mel Gorman",
        "email": "mel@csn.ul.ie",
        "time": "Mon May 24 14:32:28 2010 -0700"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Tue May 25 08:06:59 2010 -0700"
      },
      "message": "mm: compaction: add /proc trigger for memory compaction\n\nAdd a proc file /proc/sys/vm/compact_memory.  When an arbitrary value is\nwritten to the file, all zones are compacted.  The expected user of such a\ntrigger is a job scheduler that prepares the system before the target\napplication runs.\n\nSigned-off-by: Mel Gorman \u003cmel@csn.ul.ie\u003e\nAcked-by: Rik van Riel \u003criel@redhat.com\u003e\nReviewed-by: KAMEZAWA Hiroyuki \u003ckamezawa.hiroyu@jp.fujitsu.com\u003e\nReviewed-by: Minchan Kim \u003cminchan.kim@gmail.com\u003e\nReviewed-by: KOSAKI Motohiro \u003ckosaki.motohiro@jp.fujitsu.com\u003e\nReviewed-by: Christoph Lameter \u003ccl@linux-foundation.org\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    },
    {
      "commit": "748446bb6b5a9390b546af38ec899c868a9dbcf0",
      "tree": "4c27d0805a5e094b39ff938ad60dd270b953a79f",
      "parents": [
        "c175a0ce7584e5b498fff8cbdb9aa7912aa9fbba"
      ],
      "author": {
        "name": "Mel Gorman",
        "email": "mel@csn.ul.ie",
        "time": "Mon May 24 14:32:27 2010 -0700"
      },
      "committer": {
        "name": "Linus Torvalds",
        "email": "torvalds@linux-foundation.org",
        "time": "Tue May 25 08:06:59 2010 -0700"
      },
      "message": "mm: compaction: memory compaction core\n\nThis patch is the core of a mechanism which compacts memory in a zone by\nrelocating movable pages towards the end of the zone.\n\nA single compaction run involves a migration scanner and a free scanner.\nBoth scanners operate on pageblock-sized areas in the zone.  The migration\nscanner starts at the bottom of the zone and searches for all movable\npages within each area, isolating them onto a private list called\nmigratelist.  The free scanner starts at the top of the zone and searches\nfor suitable areas and consumes the free pages within making them\navailable for the migration scanner.  The pages isolated for migration are\nthen migrated to the newly isolated free pages.\n\n[aarcange@redhat.com: Fix unsafe optimisation]\n[mel@csn.ul.ie: do not schedule work on other CPUs for compaction]\nSigned-off-by: Mel Gorman \u003cmel@csn.ul.ie\u003e\nAcked-by: Rik van Riel \u003criel@redhat.com\u003e\nReviewed-by: Minchan Kim \u003cminchan.kim@gmail.com\u003e\nCc: KOSAKI Motohiro \u003ckosaki.motohiro@jp.fujitsu.com\u003e\nCc: Christoph Lameter \u003ccl@linux-foundation.org\u003e\nCc: KAMEZAWA Hiroyuki \u003ckamezawa.hiroyu@jp.fujitsu.com\u003e\nSigned-off-by: Andrew Morton \u003cakpm@linux-foundation.org\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n"
    }
  ]
}