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 SMTP id A50E86B0071 for ; Thu, 21 Jan 2010 20:09:51 -0500 (EST) Received: from m4.gw.fujitsu.co.jp ([10.0.50.74]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o0M19mfX018275 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Fri, 22 Jan 2010 10:09:48 +0900 Received: from smail (m4 [127.0.0.1]) by outgoing.m4.gw.fujitsu.co.jp (Postfix) with ESMTP id B4BE645DE6E for ; Fri, 22 Jan 2010 10:09:47 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by m4.gw.fujitsu.co.jp (Postfix) with ESMTP id 91E1245DE60 for ; Fri, 22 Jan 2010 10:09:47 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id F29E11DB8040 for ; Fri, 22 Jan 2010 10:09:46 +0900 (JST) Received: from m106.s.css.fujitsu.com (m106.s.css.fujitsu.com [10.249.87.106]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 9D6271DB803B for ; Fri, 22 Jan 2010 10:09:43 +0900 (JST) Date: Fri, 22 Jan 2010 10:06:28 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH] oom-kill: add lowmem usage aware oom kill handling Message-Id: <20100122100628.593f3394.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <28c262361001211640w4ff6d61mdf682fa706ab61e@mail.gmail.com> References: <20100121145905.84a362bb.kamezawa.hiroyu@jp.fujitsu.com> <1264087124.1818.15.camel@barrios-desktop> <20100122084856.600b2dd5.kamezawa.hiroyu@jp.fujitsu.com> <28c262361001211640w4ff6d61mdf682fa706ab61e@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: "linux-mm@kvack.org" , "akpm@linux-foundation.org" , rientjes@google.com, "linux-kernel@vger.kernel.org" List-ID: On Fri, 22 Jan 2010 09:40:17 +0900 Minchan Kim wrote: > On Fri, Jan 22, 2010 at 8:48 AM, KAMEZAWA Hiroyuki > wrote: > > On Fri, 22 Jan 2010 00:18:44 +0900 > > Minchan Kim wrote: > > > >> Hi, Kame. > >> > >> On Thu, 2010-01-21 at 14:59 +0900, KAMEZAWA Hiroyuki wrote: > >> > A patch for avoiding oom-serial-killer at lowmem shortage. > >> > Patch is onto mmotm-2010/01/15 (depends on mm-count-lowmem-rss.patch) > >> > Tested on x86-64/SMP + debug module(to allocated lowmem), works well. > >> > > >> > == > >> > From: KAMEZAWA Hiroyuki > >> > > >> > One cause of OOM-Killer is memory shortage in lower zones. > >> > (If memory is enough, lowmem_reserve_ratio works well. but..) > >> > > >> > In lowmem-shortage oom-kill, oom-killer choses a vicitim process > >> > on their vm size. But this kills a process which has lowmem memory > >> > only if it's lucky. At last, there will be an oom-serial-killer. > >> > > >> > Now, we have per-mm lowmem usage counter. We can make use of it > >> > to select a good? victim. > >> > > >> > This patch does > >> > A - add CONSTRAINT_LOWMEM to oom's constraint type. > >> > A - pass constraint to __badness() > >> > A - change calculation based on constraint. If CONSTRAINT_LOWMEM, > >> > A A use low_rss instead of vmsize. > >> > >> As far as low memory, it would be better to consider lowmem counter. > >> But as you know, {vmsize VS rss} is debatable topic. > >> Maybe someone doesn't like this idea. > >> > > About lowmem, vmsize never work well. > > > > Tend to agree with you. > I am just worried about "vmsize lovers". > > You removed considering vmsize totally. > In case of LOWMEM, lowcount considering make sense. > But never considering vmsize might be debatable. > > So personllay, I thouhg we could add more weight lowcount > in case of LOWMEM. But I chaged my mind. > I think it make OOM heurisic more complated without big benefit. > thanks. I don't want patch-drop again, either :) > Simple is best. > > >> So don't we need any test result at least? > > My test result was very artificial, so I didn't attach the result. > > > > A - Before this patch, sshd was killed at first. > > A - After this patch, memory consumer of low-rss was killed. > > Okay. You already anwsered my question by Balbir's reply. > I had a question it's real problem and how often it happens. > > > > >> If we don't have this patch, it happens several innocent process > >> killing. but we can't prevent it by this patch. > >> > > I can't catch what you mean. > > I just said your patch's benefit. > > >> Sorry for bothering you. > >> > > > > Hmm, boot option or CONFIG ? (CONFIG_OOMKILLER_EXTENSION ?) > > > > I'm now writing fork-bomb detector again and want to remove current > > "gathering child's vm_size" heuristics. I'd like to put that under > > the same config, too. > > Totally, I don't like CONFIG option for that. > But vmsize lovers also don't want to change current behavior. > So it's desirable until your fork-form detector become mature and > prove it's good. > Hmm, Okay, I'll add some. Kosaki told me sysctl is better. I'll check how it looks. > One more questions about below. > > + if (constraint != CONSTRAINT_LOWMEM) { > + list_for_each_entry(child, &p->children, sibling) { > + task_lock(child); > + if (child->mm != mm && child->mm) > + points += child->mm->total_vm/2 + 1; > + task_unlock(child); > + } > > Why didn't you consider child's lowmem counter in case of LOWMEM? > Assume process A, B, C, D. B and C are children of A. A (low_rss = 0) B (low_rss = 20) C (low_rss = 20) D (low_rss = 20) When we caluculate A's socre by above logic, A's score may be greater than B and C, D. We do targetted oom-kill as sniper, not as genocider. So, ignoreing children here is better, I think. I'll add some explanation to changelog. Thanks, -Kame -- 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