From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d23relay03.au.ibm.com (d23relay03.au.ibm.com [202.81.18.234]) by e23smtp02.au.ibm.com (8.13.1/8.13.1) with ESMTP id mAH3jPUC014160 for ; Mon, 17 Nov 2008 14:45:25 +1100 Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay03.au.ibm.com (8.13.8/8.13.8/NCO v9.1) with ESMTP id mAH3hrot2875520 for ; Mon, 17 Nov 2008 14:43:53 +1100 Received: from d23av01.au.ibm.com (loopback [127.0.0.1]) by d23av01.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id mAH3held027802 for ; Mon, 17 Nov 2008 14:43:40 +1100 Message-ID: <4920E869.9030501@linux.vnet.ibm.com> Date: Mon, 17 Nov 2008 09:13:37 +0530 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com MIME-Version: 1.0 Subject: Re: [PATCH -mm] vmscan: bail out of page reclaim after swap_cluster_max pages References: <20081113171208.6985638e@bree.surriel.com> <20081116163316.F205.KOSAKI.MOTOHIRO@jp.fujitsu.com> <20081117093832.f383bd61.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20081117093832.f383bd61.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: KOSAKI Motohiro , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: KAMEZAWA Hiroyuki wrote: > On Sun, 16 Nov 2008 16:38:56 +0900 (JST) > KOSAKI Motohiro wrote: > >> One more point. >> >>> Sometimes the VM spends the first few priority rounds rotating back >>> referenced pages and submitting IO. Once we get to a lower priority, >>> sometimes the VM ends up freeing way too many pages. >>> >>> The fix is relatively simple: in shrink_zone() we can check how many >>> pages we have already freed and break out of the loop. >>> >>> However, in order to do this we do need to know how many pages we already >>> freed, so move nr_reclaimed into scan_control. >> IIRC, Balbir-san explained the implemetation of the memcgroup >> force cache dropping feature need non bail out at the past reclaim >> throttring discussion. >> Yes, for we used that for force_empty() in the past, but see below >> I am not sure about this still right or not (iirc, memcgroup implemetation >> was largely changed). >> >> Balbir-san, Could you comment to this patch? >> >> > I'm not Balbir-san but there is no "force-cache-dropping" feature now. > (I have no plan to do that.) > > But, mem+swap controller will need to modify reclaim path to do "cache drop > first" becasue the amount of "mem+swap" will not change when "mem+swap" hit > limit. It's now set "sc.may_swap" to 0. > Yes, there have been several changes to force_empty() and its meaning, including movement of accounts. Since you've made most of the recent changes, your comments are very relevant. > Hmm, I hope memcg is a silver bullet to this kind of special? workload in > long term. :-) From my perspective, hierarchy, soft limits (sharing memory when there is no contention), some form of over commit support and getting swappiness to work correctly are very important for memcg. -- 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