From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d03relay04.boulder.ibm.com (d03relay04.boulder.ibm.com [9.17.195.106]) by e35.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id m2QIrpHL023058 for ; Wed, 26 Mar 2008 14:53:51 -0400 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by d03relay04.boulder.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m2QIrowD093572 for ; Wed, 26 Mar 2008 12:53:50 -0600 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m2QIrnuB004016 for ; Wed, 26 Mar 2008 12:53:50 -0600 From: Balbir Singh 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: owner-linux-mm@kvack.org Return-Path: 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 List-ID: 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 -- 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