From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753403AbYKHJL3 (ORCPT ); Sat, 8 Nov 2008 04:11:29 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754052AbYKHJKr (ORCPT ); Sat, 8 Nov 2008 04:10:47 -0500 Received: from e31.co.us.ibm.com ([32.97.110.149]:48803 "EHLO e31.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753996AbYKHJKp (ORCPT ); Sat, 8 Nov 2008 04:10:45 -0500 From: Balbir Singh To: linux-mm@kvack.org Cc: YAMAMOTO Takashi , Paul Menage , lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org, Nick Piggin , David Rientjes , Pavel Emelianov , Dhaval Giani , Balbir Singh , Andrew Morton , KAMEZAWA Hiroyuki Date: Sat, 08 Nov 2008 14:40:27 +0530 Message-Id: <20081108091027.32236.56400.sendpatchset@localhost.localdomain> In-Reply-To: <20081108091009.32236.26177.sendpatchset@localhost.localdomain> References: <20081108091009.32236.26177.sendpatchset@localhost.localdomain> Subject: [RFC][mm] [PATCH 1/4] Memory cgroup hierarchy documentation (v2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Documentation updates for hierarchy support Signed-off-by: Balbir Singh --- Documentation/controllers/memory.txt | 37 +++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff -puN Documentation/controllers/memory.txt~memcg-hierarchy-documentation Documentation/controllers/memory.txt --- linux-2.6.28-rc2/Documentation/controllers/memory.txt~memcg-hierarchy-documentation 2008-11-08 14:09:29.000000000 +0530 +++ linux-2.6.28-rc2-balbir/Documentation/controllers/memory.txt 2008-11-08 14:09:29.000000000 +0530 @@ -245,6 +245,43 @@ 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. Hierarchy support + +The memory controller supports a deep hierarchy and hierarchical accounting. +The hierarchy is created by creating the appropriate cgroups in the +cgroup filesystem. Consider for example, the following cgroup filesystem +hierarchy + + root + / | \ + / | \ + a b c + | \ + | \ + d e + +In the diagram above, with hierarchical accounting enabled, all memory +usage of e, is accounted to its ancestors up until the root (i.e, c and root), +that has memory.use_hierarchy enabled. If one of the ancestors goes over its +limit, the reclaim algorithm reclaims from the tasks in the ancestor and the +children of the ancestor. + +5.1 Enabling hierarchical accounting and reclaim + +The memory controller by default disables the hierarchy feature. Support +can be enabled by writing 1 to memory.use_hierarchy file of the root cgroup + +# echo 1 > memory.use_hierarchy + +The feature can be disabled by + +# echo 0 > memory.use_hierarchy + +NOTE1: Enabling/disabling will fail if the cgroup already has other +cgroups created below it. + +NOTE2: This feature can be enabled/disabled per subtree. + 5. TODO 1. Add support for accounting huge pages (as a separate controller) _ -- Balbir