From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762642AbYCZSyU (ORCPT ); Wed, 26 Mar 2008 14:54:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762360AbYCZSxy (ORCPT ); Wed, 26 Mar 2008 14:53:54 -0400 Received: from e34.co.us.ibm.com ([32.97.110.152]:50586 "EHLO e34.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762339AbYCZSxw (ORCPT ); Wed, 26 Mar 2008 14:53:52 -0400 From: Balbir Singh To: Andrew Morton , Pavel Emelianov Cc: Hugh Dickins , Sudhir Kumar , YAMAMOTO Takashi , Paul Menage , lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org, taka@valinux.co.jp, linux-mm@kvack.org, David Rientjes , Balbir Singh , KAMEZAWA Hiroyuki Date: Thu, 27 Mar 2008 00:20:29 +0530 Message-Id: <20080326185029.9465.7378.sendpatchset@localhost.localdomain> In-Reply-To: <20080326184954.9465.19379.sendpatchset@localhost.localdomain> References: <20080326184954.9465.19379.sendpatchset@localhost.localdomain> Subject: [RFC][3/3] Update documentation for virtual address space control (v2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Changelog v2 ------------ Fix typos and implement review suggestions from Randy This patch adds documentation for virtual address space control. Signed-off-by: Balbir Singh --- Documentation/controllers/memory.txt | 28 +++++++++++++++++++++++++++- 1 file changed, 27 insertions(+), 1 deletion(-) diff -puN Documentation/controllers/memory.txt~memory-controller-virtual-address-control-documentation Documentation/controllers/memory.txt --- linux-2.6.25-rc5/Documentation/controllers/memory.txt~memory-controller-virtual-address-control-documentation 2008-03-27 00:18:19.000000000 +0530 +++ linux-2.6.25-rc5-balbir/Documentation/controllers/memory.txt 2008-03-27 00:18:19.000000000 +0530 @@ -237,7 +237,33 @@ cgroup might have some charge associated tasks have migrated away from it. Such charges are automatically dropped at rmdir() if there are no tasks. -5. TODO +5. Virtual address space accounting + +A new resource counter controls the address space expansion of the tasks in +the cgroup. Address space control is provided along the same lines as +RLIMIT_AS control, which is available via getrlimit(2)/setrlimit(2). +The interface for controlling address space is provided through +"as_limit_in_bytes". The file is similar to "limit_in_bytes" w.r.t. the user +interface. Please see section 3 for more details on how to use the user +interface to get and set values. + +The "as_usage_in_bytes" file provides information about the total address +space usage of the cgroup in bytes. + +5.1 Advantages of providing this feature + +1. Control over virtual address space allows for a cgroup to fail gracefully + i.e., via a malloc or mmap failure as compared to OOM kill when no + pages can be reclaimed. +2. It provides better control over how many pages can be swapped out when + the cgroup goes over its limit. A badly setup cgroup can cause excessive + swapping. Providing control over the address space allocations ensures + that the system administrator has control over the total swapping that + can take place. + +NOTE: This feature is controlled by the CONFIG_CGROUP_MEM_RES_CTLR_AS + +6. TODO 1. Add support for accounting huge pages (as a separate controller) 2. Make per-cgroup scanner reclaim not-shared pages first _ -- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL