From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx140.postini.com [74.125.245.140]) by kanga.kvack.org (Postfix) with SMTP id EAE476B0005 for ; Sat, 6 Apr 2013 20:48:10 -0400 (EDT) Received: by mail-ie0-f171.google.com with SMTP id e14so5665177iej.16 for ; Sat, 06 Apr 2013 17:48:10 -0700 (PDT) Message-ID: <5160C244.6080807@gmail.com> Date: Sun, 07 Apr 2013 08:48:04 +0800 From: Simon Jeons MIME-Version: 1.0 Subject: Re: [PATCH v7 2/2] mm: replace hardcoded 3% with admin_reserve_pages knob References: <20130325134247.GB1393@localhost.localdomain> <515CF884.8010103@gmail.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Shewmaker Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, alan@lxorguk.ukuu.org.uk, ric.masonn@gmail.com Hi Andrew, On 04/05/2013 11:02 PM, Andrew Shewmaker wrote: > On Wed, Apr 3, 2013 at 9:50 PM, Simon Jeons wrote: >>> FAQ >>> > ... >>> * How do you calculate a minimum useful reserve? >>> >>> A user or the admin needs enough memory to login and perform >>> recovery operations, which includes, at a minimum: >>> >>> sshd or login + bash (or some other shell) + top (or ps, kill, etc.) >>> >>> For overcommit 'guess', we can sum resident set sizes (RSS). >>> On x86_64 this is about 8MB. >>> >>> For overcommit 'never', we can take the max of their virtual sizes >>> (VSZ) >>> and add the sum of their RSS. >>> On x86_64 this is about 128MB. >> >> 1.Why has this different between guess and never? > The default, overcommit 'guess' mode, only needs a reserve for > what the recovery programs will typically use. Overcommit 'never' > mode will only successfully launch an app when it can fulfill all of > its requested memory allocations--even if the app only uses a > fraction of what it asks for. VSZ has already cover RSS, is it? why account RSS again? > >> 2.You just test x86/x86_64, other platforms also will use memory overcommit, >> did you test them? > No, I haven't. Unfortunately, I don't currently have any other platforms to test > with. I'll see what I can do. > > Thanks, > > Andrew -- 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