• Mel Gorman's avatar
    mm: compaction: direct compact when a high-order allocation fails · 56de7263
    Mel Gorman authored
    Ordinarily when a high-order allocation fails, direct reclaim is entered
    to free pages to satisfy the allocation.  With this patch, it is
    determined if an allocation failed due to external fragmentation instead
    of low memory and if so, the calling process will compact until a suitable
    page is freed.  Compaction by moving pages in memory is considerably
    cheaper than paging out to disk and works where there are locked pages or
    no swap.  If compaction fails to free a page of a suitable size, then
    reclaim will still occur.
    Direct compaction returns as soon as possible.  As each block is
    compacted, it is checked if a suitable page has been freed and if so, it
    [akpm@linux-foundation.org: Fix build errors]
    [aarcange@redhat.com: fix count_vm_event preempt in memory compaction direct reclaim]
    Signed-off-by: default avatarMel Gorman <mel@csn.ul.ie>
    Acked-by: default avatarRik van Riel <riel@redhat.com>
    Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
    Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
    Cc: Christoph Lameter <cl@linux-foundation.org>
    Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
    Signed-off-by: default avatarAndrea Arcangeli <aarcange@redhat.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
vmstat.c 28.5 KB