From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from d03relay02.boulder.ibm.com (d03relay02.boulder.ibm.com [9.17.195.227]) by e36.co.us.ibm.com (8.13.8/8.13.8) with ESMTP id m2GHVhjb024892 for ; Sun, 16 Mar 2008 13:31:43 -0400 Received: from d03av04.boulder.ibm.com (d03av04.boulder.ibm.com [9.17.195.170]) by d03relay02.boulder.ibm.com (8.13.8/8.13.8/NCO v8.7) with ESMTP id m2GHVhUW194034 for ; Sun, 16 Mar 2008 11:31:43 -0600 Received: from d03av04.boulder.ibm.com (loopback [127.0.0.1]) by d03av04.boulder.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m2GHVg22009234 for ; Sun, 16 Mar 2008 11:31:43 -0600 From: Balbir Singh Date: Sun, 16 Mar 2008 23:00:17 +0530 Message-Id: <20080316173017.8812.41614.sendpatchset@localhost.localdomain> In-Reply-To: <20080316172942.8812.56051.sendpatchset@localhost.localdomain> References: <20080316172942.8812.56051.sendpatchset@localhost.localdomain> Subject: [RFC][3/3] Update documentation for virtual address space control Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org Cc: Hugh Dickins , Sudhir Kumar , YAMAMOTO Takashi , Paul Menage , lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org, taka@valinux.co.jp, David Rientjes , Pavel Emelianov , Balbir Singh , Andrew Morton , KAMEZAWA Hiroyuki List-ID: This patch adds documentation for virtual address space control. Signed-off-by: Balbir Singh --- Documentation/controllers/memory.txt | 26 +++++++++++++++++++++++++- 1 file changed, 25 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 2008-03-16 22:57:44.000000000 +0530 +++ linux-2.6.25-rc5-balbir/Documentation/controllers/memory.txt 2008-03-16 22:57:44.000000000 +0530 @@ -237,7 +237,31 @@ 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 it's 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. + +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