From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sd0109e.au.ibm.com (d23rh905.au.ibm.com [202.81.18.225]) by e23smtp04.au.ibm.com (8.13.1/8.13.1) with ESMTP id m6KNhtTF024389 for ; Mon, 21 Jul 2008 09:43:55 +1000 Received: from d23av02.au.ibm.com (d23av02.au.ibm.com [9.190.235.138]) by sd0109e.au.ibm.com (8.13.8/8.13.8/NCO v9.0) with ESMTP id m6KNiqnu280292 for ; Mon, 21 Jul 2008 09:44:52 +1000 Received: from d23av02.au.ibm.com (loopback [127.0.0.1]) by d23av02.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m6KNipAQ012908 for ; Mon, 21 Jul 2008 09:44:51 +1000 Message-ID: <4883CDEB.2030403@linux.vnet.ibm.com> Date: Sun, 20 Jul 2008 19:44:43 -0400 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com MIME-Version: 1.0 Subject: Re: [mmtom] please drop memcg-handle-swap-cache set (memcg handle swap cache rework). References: <20080717124556.3e4b6e20.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20080717124556.3e4b6e20.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: "linux-mm@kvack.org" , "xemul@openvz.org" , "nishimura@mxp.nes.nec.co.jp" , Andrew Morton , "kosaki.motohiro@jp.fujitsu.com" , "hugh@veritas.com" List-ID: KAMEZAWA Hiroyuki wrote: > Now, SwapCache is handled by memcg (in -mm) but it became complicated than I thought of. > > followings are queued in -mm now. > memcg-handle-swap-cache.patch > memcg-handle-swap-cache-fix.patch > memcg-handle-swap-cache-fix-shmem-page-migration-incorrectness-on-memcgroup.patch > > And I have memcg-handle-shmem-swap-cache-fix.patch.... > > Balbir argued that "This is too complicated!", ok, let's rework. > Thanks, it was complicated and simplification is always welcome! > Andrew, could you drop above 3 patches ? I'd like to retry with clear logic. > > I'm testing this new version now. Basic logic is not changed but corner case > handling is clearer than previous one. If there is something unclear, > please tell me. I'd like to write easy-to-understand one. > > == > This patch tries to catch SwapCache usage by memcg in following Rule. > > 1. just ignore add_to_swap_cache() > 2. if a page is uncharged, > (a) don't uncharge when PageSwapCache(page) > (b) don't uncharge when the page is mapped. > (c) don't uncharge when the page is still on radix-tree. > This can be checked by (page->mapping && !PageAnon(page)) > > 3. __delete_from_swap_cache() calles uncharge after clearing PageSwapCache flag. > 4. mem_cgroup_uncharge_cache() is called only after page->mapping is cleared. > 5. migration has some corner case and handled. > My understanding of this patchset now is that If the page was ever mapped or cached, we don't tweak add_to_swap_cache(), instead, we keep the page around in the memcg, till it is removed from swap cache. Is my understanding of your intent correct? [snip] -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL -- 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