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SubjectRe: [patch] memcg: skip scanning active lists based on individual size
On Wed, Aug 31, 2011 at 6:08 PM, Johannes Weiner <> 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 <>
> Cc: Rik van Riel <>
> Cc: KOSAKI Motohiro <>
> Cc: KAMEZAWA Hiroyuki <>
> Cc: Daisuke Nishimura <>
> Cc: Balbir Singh <>

Reviewed-by: Minchan Kim <>

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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