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 8597760021B for ; Thu, 31 Dec 2009 03:43:42 -0500 (EST) Date: Thu, 31 Dec 2009 08:43:39 +0000 (GMT) From: Hugh Dickins Subject: Re: [PATCH 2/3 -mmotm-2009-12-10-17-19] Count zero page as file_rss In-Reply-To: <28c262360912301841r3ed43d31yc677fbc3a01fe5bb@mail.gmail.com> Message-ID: References: <4B38876F.6010204@gmail.com> <28c262360912301841r3ed43d31yc677fbc3a01fe5bb@mail.gmail.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: Minchan Kim Cc: Andrew Morton , LKML , linux-mm , KAMEZAWA Hiroyuki List-ID: On Thu, 31 Dec 2009, Minchan Kim wrote: > On Thu, Dec 31, 2009 at 1:49 AM, Hugh Dickins > wrote: > > > > 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. > > Thanks. > If we think this patch is need, I will repost path with fix it. > > What do you think? If someone comes up with a convincing case in which their system is behaving significantly worse because the zero page is not being counted in rss now, then we shall probably want your patch. But I still don't yet see a reason to add code just to keep the anon_rss+file_rss number looking the same as it was before, in this exceptional case where there's a significant number of zero pages. Hugh -- 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