From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lb0-f200.google.com (mail-lb0-f200.google.com [209.85.217.200]) by kanga.kvack.org (Postfix) with ESMTP id 6124A6B007E for ; Fri, 13 May 2016 05:52:33 -0400 (EDT) Received: by mail-lb0-f200.google.com with SMTP id f14so25852365lbb.2 for ; Fri, 13 May 2016 02:52:33 -0700 (PDT) Received: from mail-wm0-f66.google.com (mail-wm0-f66.google.com. [74.125.82.66]) by mx.google.com with ESMTPS id mw4si21355593wjb.85.2016.05.13.02.52.31 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 13 May 2016 02:52:31 -0700 (PDT) Received: by mail-wm0-f66.google.com with SMTP id e201so2609264wme.2 for ; Fri, 13 May 2016 02:52:31 -0700 (PDT) Date: Fri, 13 May 2016 11:52:30 +0200 From: Michal Hocko Subject: Re: [PATCH] mm: add config option to select the initial overcommit mode Message-ID: <20160513095230.GI20141@dhcp22.suse.cz> References: <5731CC6E.3080807@laposte.net> <20160513080458.GF20141@dhcp22.suse.cz> <573593EE.6010502@free.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <573593EE.6010502@free.fr> Sender: owner-linux-mm@kvack.org List-ID: To: Mason Cc: Sebastian Frias , linux-mm@kvack.org, Andrew Morton , Linus Torvalds , LKML On Fri 13-05-16 10:44:30, Mason wrote: > On 13/05/2016 10:04, Michal Hocko wrote: > > > On Tue 10-05-16 13:56:30, Sebastian Frias wrote: > > [...] > >> NOTE: I understand that the overcommit mode can be changed dynamically thru > >> sysctl, but on embedded systems, where we know in advance that overcommit > >> will be disabled, there's no reason to postpone such setting. > > > > To be honest I am not particularly happy about yet another config > > option. At least not without a strong reason (the one above doesn't > > sound that way). The config space is really large already. > > So why a later initialization matters at all? Early userspace shouldn't > > consume too much address space to blow up later, no? > > One thing I'm not quite clear on is: why was the default set > to over-commit on? Because many applications simply rely on large and sparsely used address space, I guess. That's why the default is GUESS where we ignore the cumulative charges and simply check the current state and blow up only when the current request is way too large. -- Michal Hocko SUSE Labs -- 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