Messages in this thread | | | Date | Wed, 31 Aug 2011 19:13:34 +0900 | Subject | Re: [patch] memcg: skip scanning active lists based on individual size | From | Minchan Kim <> |
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On Wed, Aug 31, 2011 at 6:08 PM, Johannes Weiner <jweiner@redhat.com> wrote: > Reclaim decides to skip scanning an active list when the corresponding > inactive list is above a certain size in comparison to leave the > assumed working set alone while there are still enough reclaim > candidates around. > > The memcg implementation of comparing those lists instead reports > whether the whole memcg is low on the requested type of inactive > pages, considering all nodes and zones. > > This can lead to an oversized active list not being scanned because of > the state of the other lists in the memcg, as well as an active list > being scanned while its corresponding inactive list has enough pages. > > Not only is this wrong, it's also a scalability hazard, because the > global memory state over all nodes and zones has to be gathered for > each memcg and zone scanned. > > Make these calculations purely based on the size of the two LRU lists > that are actually affected by the outcome of the decision. > > Signed-off-by: Johannes Weiner <jweiner@redhat.com> > Cc: Rik van Riel <riel@redhat.com> > Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> > Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> > Cc: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
I can't understand why memcg is designed for considering all nodes and zones. Is it a mistake or on purpose? Maybe Kame or Balbir can answer it.
Anyway, this change does make sense to me.
Nitpick: Please remove inactive_ratio in Documentation/cgroups/memory.txt. I think it would be better to separate it into another patch.
-- Kind regards, Minchan Kim
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