From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967542AbXHMPwh (ORCPT ); Mon, 13 Aug 2007 11:52:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030643AbXHMOOE (ORCPT ); Mon, 13 Aug 2007 10:14:04 -0400 Received: from atrey.karlin.mff.cuni.cz ([195.113.31.123]:51855 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S946505AbXHMOOB (ORCPT ); Mon, 13 Aug 2007 10:14:01 -0400 X-Greylist: delayed 1653 seconds by postgrey-1.27 at vger.kernel.org; Mon, 13 Aug 2007 10:14:00 EDT Date: Mon, 13 Aug 2007 15:46:26 +0200 From: Pavel Machek To: Andrew Morton , kernel list Cc: andrea@suse.de, npiggin@suse.de, peterz@infradead.org Subject: min_free_kbytes documentation, /proc/sys/vm docs Message-ID: <20070813134626.GA7305@atrey.karlin.mff.cuni.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! min_free_kbytes documentation says: min_free_kbytes: This is used to force the Linux VM to keep a minimum number of kilobytes free. The VM uses this number to compute a pages_min value for each lowmem zone in the system. Each lowmem zone gets a number of reserved free pages based proportionally on its size. ...which is not too helpful :-(. In particular, should kernel survive setting this to 0 and still work reliably? IOW is this performance-only tweak, or does it correctness implications? I guess it should also say something like "do not set this to more than half of your physical RAM (or half of lowmem?) or you get an instant OOM". Plus, lowmem_reserve_ratio seems to be undocumented. Pavel (trying to come up with agressive settings, so that swap over ata over ethernet finally breaks). -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html