From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 4CC1B5F0001 for ; Wed, 8 Apr 2009 05:03:07 -0400 (EDT) Received: from d28relay04.in.ibm.com (d28relay04.in.ibm.com [9.184.220.61]) by e28smtp03.in.ibm.com (8.13.1/8.13.1) with ESMTP id n38933N1010544 for ; Wed, 8 Apr 2009 14:33:03 +0530 Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay04.in.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n3893DDu1458190 for ; Wed, 8 Apr 2009 14:33:13 +0530 Received: from d28av04.in.ibm.com (loopback [127.0.0.1]) by d28av04.in.ibm.com (8.13.1/8.13.3) with ESMTP id n38932JB011411 for ; Wed, 8 Apr 2009 19:03:02 +1000 Date: Wed, 8 Apr 2009 14:32:33 +0530 From: Balbir Singh Subject: Re: [RFI] Shared accounting for memory resource controller Message-ID: <20090408090233.GH7082@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20090408052904.GY7082@balbir.in.ibm.com> <20090408151529.fd6626c2.kamezawa.hiroyu@jp.fujitsu.com> <20090408070401.GC7082@balbir.in.ibm.com> <20090408160733.4813cb8d.kamezawa.hiroyu@jp.fujitsu.com> <20090408071115.GD7082@balbir.in.ibm.com> <20090408161824.26f47077.kamezawa.hiroyu@jp.fujitsu.com> <20090408074809.GF7082@balbir.in.ibm.com> <20090408170341.437c215b.kamezawa.hiroyu@jp.fujitsu.com> <20090408084952.GG7082@balbir.in.ibm.com> <20090408175409.eb0818db.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20090408175409.eb0818db.kamezawa.hiroyu@jp.fujitsu.com> Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , Andrew Morton , "lizf@cn.fujitsu.com" , Rik van Riel , Bharata B Rao , Dhaval Giani , KOSAKI Motohiro , "linux-kernel@vger.kernel.org" List-ID: * KAMEZAWA Hiroyuki [2009-04-08 17:54:09]: > On Wed, 8 Apr 2009 14:19:52 +0530 > Balbir Singh wrote: > > > * KAMEZAWA Hiroyuki [2009-04-08 17:03:41]: > > > > > On Wed, 8 Apr 2009 13:18:09 +0530 > > > Balbir Singh wrote: > > > > > > > > > 3. Using the above, we can then try to (using an algorithm you > > > > > > proposed), try to do some work for figuring out the shared percentage. > > > > > > > > > > > This is the point. At last. Why "# of shared pages" is important ? > > > > > > > > > > > > > I posted this in my motivation yesterday. # of shared pages can help > > > > plan the system better and the size of the cgroup. A cgroup might have > > > > small usage_in_bytes but large number of shared pages. We need a > > > > metric that can help figure out the fair usage of the cgroup. > > > > > > > I don't fully understand but NR_FILE_MAPPED is an information in /proc/meminfo. > > > I personally think I want to support information in /proc/meminfo per memcg. > > > > > > Hmm ? then, if you add a hook, it seems > > > == mm/rmap.c > > > 689 void page_add_file_rmap(struct page *page) > > > 690 { > > > 691 if (atomic_inc_and_test(&page->_mapcount)) > > > 692 __inc_zone_page_state(page, NR_FILE_MAPPED); > > > 693 } > > > == page_remove_rmap(struct page *page) > > > 739 __dec_zone_page_state(page, > > > 740 PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED); > > > == > > > > > > Is good place to go, maybe. > > > > > > page->page_cgroup->mem_cgroup-> inc/dec counter ? > > > > > > Maybe the patch itself will be simple, overhead is unknown.. > > > > I thought of the same thing, but then moved to the following > > > > ... mem_cgroup_charge_statistics(..) { > > if (page_mapcount(page) == 0 && page_is_file_cache(page)) > > __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_FILE_RSS, val); > > > > But I've not yet tested the end result > > > I think > - at uncharge: > charge_statistics is only called when FILE CACHE is removed from radix-tree. > mem_cgroup_uncharge() is called only when PageAnon(page). Good point, I missed it, testing would have caught it. > - at charge: > charge_statistics is only called when FILE CACHE is added to radix-tree. > > This "checking only radix-tree insert/delete" help us to remove most of overheads > on FILE CACHE. > > So, adding new hooks to page_add_file_rmap() and page_remove_rmap() > is a way to go. (and easy to understand because we account it at the same time > NR_FILE_MAPPED is modified.) Agreed. -- Balbir -- 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