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    mm: compaction: add a tunable that decides when memory should be compacted and... · 5e771905
    Mel Gorman 提交于
    mm: compaction: add a tunable that decides when memory should be compacted and when it should be reclaimed
    
    The kernel applies some heuristics when deciding if memory should be
    compacted or reclaimed to satisfy a high-order allocation.  One of these
    is based on the fragmentation.  If the index is below 500, memory will not
    be compacted.  This choice is arbitrary and not based on data.  To help
    optimise the system and set a sensible default for this value, this patch
    adds a sysctl extfrag_threshold.  The kernel will only compact memory if
    the fragmentation index is above the extfrag_threshold.
    
    [randy.dunlap@oracle.com: Fix build errors when proc fs is not configured]
    Signed-off-by: NMel Gorman <mel@csn.ul.ie>
    Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Minchan 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: NAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
    5e771905
sysctl.c 68.3 KB