lkml.org 
[lkml]   [2011]   [Aug]   [31]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch] memcg: skip scanning active lists based on individual size
On Wed, 31 Aug 2011 19:13:34 +0900
Minchan Kim <minchan.kim@gmail.com> wrote:

> 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?

It's purpose. memcg just takes care of the amount of pages.
Them, any performance numbers ?


But, hmm, this change may be good for softlimit and your work.

I'll ack when you add performance numbers in changelog.

Thanks,
-Kame



\
 
 \ /
  Last update: 2011-09-01 02:19    [from the cache]
©2003-2011 Jasper Spaans