Re: [RFD][PATCH] memcg: Move Usage at Task Move

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

On Wed, 11 Jun 2008 13:29:09 +0900
Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> wrote:

> On Wed, 11 Jun 2008 13:14:37 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > On Wed, 11 Jun 2008 12:44:46 +0900 (JST)
> > yamamoto@valinux.co.jp (YAMAMOTO Takashi) wrote:
> > 
> > > > I'm now considering following logic. How do you think ?
> > > > 
> > > > Assume: move TASK from group:CURR to group:DEST.
> > > > 
> > > > == move_task(TASK, CURR, DEST)
> > > > 
> > > > if (DEST's limit is unlimited)
> > > > 	moving TASK
> > > > 	return success.
> > > > 
> > > > usage = check_usage_of_task(TASK).
> > > > 
> > > > /* try to reserve enough room in destionation */
> > > > if (try_to_reserve_enough_room(DEST, usage)) {
> > > > 	move TASK to DEST and move pages AMAP.
> > > > 	/* usage_of_task(TASK) can be changed while we do this.
> > > > 	   Then, we move AMAP. */
> > > > 	return success;
> > > > }
> > > > return failure.
> > > > ==
> > > 
> > > AMAP means that you might leave some random charges in CURR?
> > > 
> > yes. but we can reduce bad case by some way 
> >  - reserve more than necessary.
> >  or
> >  - read_lock mm->sem while move.
> > 
> I preffer the latter.
> Though it's expencive, I think moving a task would not happen
> so offen.
> 
Sure.

I'd like to write one and post as RFC. (hopefully in this week)

Thanks,
-Kame






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