From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 51BF3600068 for ; Sun, 3 Jan 2010 19:47:13 -0500 (EST) Received: by pzk27 with SMTP id 27so8333253pzk.12 for ; Sun, 03 Jan 2010 16:47:11 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20100104084347.c36d9855.kamezawa.hiroyu@jp.fujitsu.com> References: <4B38876F.6010204@gmail.com> <20100104084347.c36d9855.kamezawa.hiroyu@jp.fujitsu.com> Date: Mon, 4 Jan 2010 09:47:11 +0900 Message-ID: <28c262361001031647r602fcdbeve56dbf4da4e31254@mail.gmail.com> Subject: Re: [PATCH 2/3 -mmotm-2009-12-10-17-19] Count zero page as file_rss From: Minchan Kim Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Hugh Dickins , Andrew Morton , LKML , linux-mm List-ID: On Mon, Jan 4, 2010 at 8:43 AM, KAMEZAWA Hiroyuki wrote: > On Wed, 30 Dec 2009 16:49:52 +0000 (GMT) > Hugh Dickins wrote: > >> > > >> > > Kame reported following as >> > > "Before starting zero-page works, I checked "questions" in lkml and >> > > found some reports that some applications start to go OOM after zero= -page >> > > removal. >> > > >> > > For me, I know one of my customer's application depends on behavior = of >> > > zero page (on RHEL5). So, I tried to add again it before RHEL6 becau= se >> > > I think removal of zero-page corrupts compatibility." >> > > >> > > So how about adding zero page as file_rss again for compatibility? >> >> I think not. >> >> KAMEZAWA-san can correct me (when he returns in the New Year) if I'm >> wrong, but I don't think his customer's OOMs had anything to do with >> whether the ZERO_PAGE was counted in file_rss or not: the OOMs came >> from the fact that many pages were being used up where just the one >> ZERO_PAGE had been good before. =C2=A0Wouldn't he have complained if the >> zero_pfn patches hadn't solved that problem? >> >> You are right that I completely overlooked the issue of whether to >> include the ZERO_PAGE in rss counts (now being a !vm_normal_page, >> it was just natural to leave it out); and I overlooked the fact that >> it used to be counted into file_rss in the old days (being !PageAnon). >> >> So I'm certainly at fault for that, and thank you for bringing the >> issue to attention; but once considered, I can't actually see a good >> reason why we should add code to count ZERO_PAGEs into file_rss now. >> And if this patch falls, then 1/3 and 3/3 would fall also. >> >> And the patch below would be incomplete anyway, wouldn't it? >> There would need to be a matching change to zap_pte_range(), >> but I don't see that. >> >> We really don't want to be adding more and more ZERO_PAGE/zero_pfn >> tests around the place if we can avoid them: KOSAKI-san has a strong >> argument for adding such a test in kernel/futex.c, but I don't the >> argument here. >> > > I agree that ZERO_PAGE shouldn't be counted as rss. Now, I feel that old > counting method(in old zero-page implementation) was bad. > > Minchan-san, I'm sorry for noise. That's all right. It was my mistake. I will drop this and repost Matt and Hugh's ACK version. Thanks for all. :) > > Thanks, > -Kame > > > > --=20 Kind regards, Minchan Kim -- 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