From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id 83D1F6B01FA for ; Tue, 30 Mar 2010 01:38:37 -0400 (EDT) Date: Tue, 30 Mar 2010 14:30:38 +0900 From: Daisuke Nishimura Subject: Re: [PATCH(v2) -mmotm 2/2] memcg move charge of shmem at task migration Message-Id: <20100330143038.422459da.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20100330050050.GA3308@balbir.in.ibm.com> References: <20100329120243.af6bfeac.nishimura@mxp.nes.nec.co.jp> <20100329120359.1c6a277d.nishimura@mxp.nes.nec.co.jp> <20100329133645.e3bde19f.kamezawa.hiroyu@jp.fujitsu.com> <20100330103301.b0d20f7e.nishimura@mxp.nes.nec.co.jp> <20100330112301.f5bb49d7.kamezawa.hiroyu@jp.fujitsu.com> <20100330114903.476af77e.nishimura@mxp.nes.nec.co.jp> <20100330121119.fcc7d45b.kamezawa.hiroyu@jp.fujitsu.com> <20100330130648.ad559645.nishimura@mxp.nes.nec.co.jp> <20100330135159.025b9366.kamezawa.hiroyu@jp.fujitsu.com> <20100330050050.GA3308@balbir.in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Balbir Singh Cc: KAMEZAWA Hiroyuki , linux-mm , Andrew Morton , Daisuke Nishimura List-ID: On Tue, 30 Mar 2010 10:30:50 +0530, Balbir Singh wrote: > * KAMEZAWA Hiroyuki [2010-03-30 13:51:59]: > > > On Tue, 30 Mar 2010 13:06:48 +0900 > > Daisuke Nishimura wrote: > > > > > On Tue, 30 Mar 2010 12:11:19 +0900, KAMEZAWA Hiroyuki wrote: > > > > On Tue, 30 Mar 2010 11:49:03 +0900 > > > > Daisuke Nishimura wrote: > > > > > > > > > On Tue, 30 Mar 2010 11:23:01 +0900, KAMEZAWA Hiroyuki wrote: > > > > > > SHARED mapped file cache is not moved by patch [1/2] ??? > > > > > > It sounds strange. > > > > > > > > > > > hmm, I'm sorry I'm not so good at user applications, but is it usual to use > > > > > VM_SHARED file caches(!tmpfs) ? > > > > > And is it better for us to move them only when page_mapcount() == 1 ? > > > > > > > > > > > > > Considering shared library which has only one user, moving MAP_SHARED makes sense. > > > > Unfortunately, there are people who creates their own shared library just for > > > > their private dlopen() etc. (shared library for private use...) > > > > > > > > So, I think moving MAP_SHARED files makes sense. > > > > > > IIRC, the libraries are loaded with MAP_PRIVATE and MAP_SHARED is not > set. > Thank you for your information. > > > Thank you for your explanations. > > > I'll update my patches to allow to move MAP_SHARED(but page_mapcount() == 1) > > > file caches, and resend. > > > > > > > Hmm, considering again...current summary is following...right ? > > > > - If page is an anon, it's not moved if page_mapcount() > 2. > > - If page is a page cache, it's not moved if page_mapcount() > 2. > > - If page is a shmem, it's not moved regardless of mapcount. > > - If pte is swap, it's not moved refcnt > 2. > > Right. > > I think following is straightforward and simple. > > > > - If page is an anon or swap of anon, it's not moved if referer > 2. > > What is referer in this context? The cgroup refering to the page? > > > (i.e. inherited from it's parent) > > - If page is file,shmem or swap of shmem, it's moved regardless of referer. > > But pages only under "from" memcg can be moved. > > > > I doubt adding too much speciality to shmem is not good. > > > > Yep, I tend to agree, but I need to take a closer look again at the > patches. > I agree it would be more simple. I selected the current policy because I was not sure whether we should move file caches(!tmpfs) with mapcount > 1, and, IMHO, shared memory and file caches are different for users. But it's O.K. for me to change current policy. 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