Re: [PATCH V7 2/2] mm: memcg detect no memcgs above softlimit under zone reclaim

[Rik van Riel <riel@redhat.com>]

On 08/06/2012 11:11 AM, Michal Hocko wrote:
> On Mon 06-08-12 10:27:25, Rik van Riel wrote:

>>> So you think we shouldn't do the full round over memcgs in shrink_zone a
>>> and rather do it oom way to pick up a victim and hammer it?
>>
>> Not hammer it too far.  Only until its score ends up well
>> below (25% lower?) than that of the second highest scoring
>> list.
>>
>> That way all the lists get hammered a little bit, in turn.
>
> How do we provide the soft limit guarantee then?
>
> [...]

The easiest way would be to find the top 2 or 3 scoring memcgs
when we reclaim memory. After reclaiming some pages, recalculate
the scores of just these top lists, and see if the list we started
out with now has a lower score than the second one.

Once we have reclaimed some from each of the 2 or 3 lists, we can
go back and find the highest priority lists again.

Direct reclaim only reclaims a little bit at a time, anyway.

For kswapd, we could also remember the number of pages the group
has in excess of its soft limit, and recalculate after that...

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