From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932647AbVHTDSw (ORCPT ); Fri, 19 Aug 2005 23:18:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932356AbVHTDSw (ORCPT ); Fri, 19 Aug 2005 23:18:52 -0400 Received: from siaag1ah.compuserve.com ([149.174.40.14]:45928 "EHLO siaag1ah.compuserve.com") by vger.kernel.org with ESMTP id S932647AbVHTDSw (ORCPT ); Fri, 19 Aug 2005 23:18:52 -0400 Date: Fri, 19 Aug 2005 23:14:39 -0400 From: Chuck Ebbert <76306.1226@compuserve.com> Subject: [patch 2.6.13-rc6] docs: fix misinformation about overcommit_memory To: linux-kernel Cc: Andrew Morton , Linus Torvalds Message-ID: <200508192318_MC3-1-A7AE-1D7A@compuserve.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Someone complained about the docs for vm_overcommit_memory being wrong. This patch copies the text from the vm documentation into procfs. Please apply. Signed-off-by: Chuck Ebbert <76306.1226@compuserve.com> Documentation/filesystems/proc.txt | 29 +++++++++++++++++++---------- 1 files changed, 19 insertions(+), 10 deletions(-) --- 2.6.13-rc6c.orig/Documentation/filesystems/proc.txt +++ 2.6.13-rc6c/Documentation/filesystems/proc.txt @@ -1240,16 +1240,25 @@ swap-intensive. overcommit_memory ----------------- -This file contains one value. The following algorithm is used to decide if -there's enough memory: if the value of overcommit_memory is positive, then -there's always enough memory. This is a useful feature, since programs often -malloc() huge amounts of memory 'just in case', while they only use a small -part of it. Leaving this value at 0 will lead to the failure of such a huge -malloc(), when in fact the system has enough memory for the program to run. - -On the other hand, enabling this feature can cause you to run out of memory -and thrash the system to death, so large and/or important servers will want to -set this value to 0. +Controls overcommit of system memory: + +0 - Heuristic overcommit handling. Obvious overcommits of + address space are refused. Used for a typical system. It + ensures a seriously wild allocation fails while allowing + overcommit to reduce swap usage. root is allowed to + allocate slighly more memory in this mode. This is the + default. + +1 - Always overcommit. Appropriate for some scientific + applications. + +2 - Don't overcommit. The total address space commit + for the system is not permitted to exceed swap + a + configurable percentage (default is 50) of physical RAM. + Depending on the percentage you use, in most situations + this means a process will not be killed while accessing + pages but will receive errors on memory allocation as + appropriate. nr_hugepages and hugetlb_shm_group ---------------------------------- __ Chuck