Messages in this thread | | | Date | Tue, 16 Feb 2010 17:15:53 +1100 | From | Nick Piggin <> | Subject | Re: [patch -mm 2/9 v2] oom: sacrifice child with highest badness score for parent |
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On Mon, Feb 15, 2010 at 02:20:03PM -0800, David Rientjes wrote: > When a task is chosen for oom kill, the oom killer first attempts to > sacrifice a child not sharing its parent's memory instead. > Unfortunately, this often kills in a seemingly random fashion based on > the ordering of the selected task's child list. Additionally, it is not > guaranteed at all to free a large amount of memory that we need to > prevent additional oom killing in the very near future. > > Instead, we now only attempt to sacrifice the worst child not sharing its > parent's memory, if one exists. The worst child is indicated with the > highest badness() score. This serves two advantages: we kill a > memory-hogging task more often, and we allow the configurable > /proc/pid/oom_adj value to be considered as a factor in which child to > kill. > > Reviewers may observe that the previous implementation would iterate > through the children and attempt to kill each until one was successful > and then the parent if none were found while the new code simply kills > the most memory-hogging task or the parent. Note that the only time > oom_kill_task() fails, however, is when a child does not have an mm or > has a /proc/pid/oom_adj of OOM_DISABLE. badness() returns 0 for both > cases, so the final oom_kill_task() will always succeed. > > Acked-by: Rik van Riel <riel@redhat.com> > Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > Reviewed-by: Minchan Kim <minchan.kim@gmail.com> > Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Nick Piggin <npiggin@suse.de>
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