From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Fri, 4 Jul 2008 21:33:01 +0900 From: Daisuke Nishimura Subject: Re: [PATCH -mm 5/5] swapcgroup (v3): implement force_empty Message-Id: <20080704213301.7d476941.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20080704191638.b63892f5.kamezawa.hiroyu@jp.fujitsu.com> References: <20080704151536.e5384231.nishimura@mxp.nes.nec.co.jp> <20080704152423.f65932b3.nishimura@mxp.nes.nec.co.jp> <20080704191638.b63892f5.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: nishimura@mxp.nes.nec.co.jp, Linux Containers , Linux MM , Balbir Singh , Pavel Emelyanov , KOSAKI Motohiro , YAMAMOTO Takashi , Hugh Dickins , IKEDA Munehiro List-ID: On Fri, 4 Jul 2008 19:16:38 +0900, KAMEZAWA Hiroyuki wrote: > On Fri, 4 Jul 2008 15:24:23 +0900 > Daisuke Nishimura wrote: > > > This patch implements force_empty of swapcgroup. > > > > Currently, it simply uncharges all the charges from the group. > > > > I think there can be other implementations. > > > > What I thought are: > > - move all the charges to its parent. > > - unuse(swap in) all the swap charged to the group. > > > 3. move all swap back to memory (see swapoff.) > > Do you mean swapping in all the swap including used by other groups? It would be one choice anyway. > > But in any case, I think before implementing this way, > > hierarchy and move charges support are needed. > > > > So I think this is enough for the first step. > > > > I don't think hierarchy/automatic-load-balancer for swap cg is necessary. It's the problem of how the "hierarchy" would be, I think. I'm saying "hierarchy" here just to mean "some kind of feature where a parent includes their children". I think "hierarchy" is needed if we implement the choice 1 above, and I personally think it would be the best choice. > Hmm...but handling limit_change (at least, returns -EBUSY) will be necessary. I think so too. But I'm not sure now it's good or bad to support shrinking at limit_change about swap. Shrinking swap means increasing the memory usage and that may cause another swapout. > Do you consider a some magical way to move pages in swap back to memory ? > In this patch, I modified the find_next_to_unuse() to find the entry charged to a specific group. It might be possible to modify try_to_unuse()(or define another function based on try_to_unuse()) to reduce swap usage of a specified group down to some threashold. But, I think, one problem here is from which device the swaps should be back to memory, or usage balance between swap devices. > In general, I like this set but we can't change the limit on demand. (maybe) > (just putting it to TO-DO-List is okay to me.) > I'm sorry but what do you mean by "change the limit on demand"? Could you explain more? Thanks, Daisuke Nishimura. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org