Re: [RFC][PATCH 1/6] memcg: free all at rmdir

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Thu, 13 Nov 2008 08:57:07 +0530
Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> > On Thu, 13 Nov 2008 08:44:59 +0530
> > Balbir Singh <balbir@linux.vnet.ibm.com> wrote:
> > 
> >> KAMEZAWA Hiroyuki wrote:
> >>> On Wed, 12 Nov 2008 16:07:58 -0800
> >>> Andrew Morton <akpm@linux-foundation.org> wrote:
> >>>> If we do this then we can make the above "keep" behaviour non-optional,
> >>>> and the operator gets to choose whether or not to drop the caches
> >>>> before doing the rmdir.
> >>>>
> >>>> Plus, we get a new per-memcg drop_caches capability.  And it's a nicer
> >>>> interface, and it doesn't have the obvious races which on_rmdir has,
> >>>> etc.
> >>>>
> >>>> hm?
> >>>>
> >>> Balbir, how would you want to do ?
> >>>
> >>> I planned to post shrink_uage patch later (it's easy to be implemented) regardless
> >>> of acceptance of this patch.
> >>>
> >>> So, I think we should add shrink_usage now and drop this is a way to go.
> >> I am a bit concerned about dropping stuff at will later. Ubuntu 8.10 has memory
> >> controller enabled and we exposed memory.force_empty interface there and now
> >> we've dropped it (bad on our part). I think we should have deprecated it and
> >> dropped it later.
> >>
> > I *was* documented as "for debug only".
> > 
> 
> I know, but I suspect users won't. I am not blaming you in person, just trying
> the find way to do such things. I think I've seen sysfs add a deprecated option
> and put all deprecated files there, they are only created if someone cares about
> them.
>
Ah, but it should be done in cgroup layer. 

> > Hmm, adding force_empty again to do "shrink usage to 0" is another choice.
> 
> Yes, sounds reasonable.
> 
ok, will post a patch today.

Thanks,
-Kame

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