From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <48BBB936.5040002@openvz.org> Date: Mon, 01 Sep 2008 13:43:18 +0400 From: Pavel Emelyanov MIME-Version: 1.0 Subject: Re: [RFC][PATCH] Remove cgroup member from struct page References: <20080831174756.GA25790@balbir.in.ibm.com> <48BBAFDD.1000902@openvz.org> <48BBB326.3080505@linux.vnet.ibm.com> In-Reply-To: <48BBB326.3080505@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: balbir@linux.vnet.ibm.com Cc: Andrew Morton , hugh@veritas.com, kamezawa.hiroyu@jp.fujitsu.com, menage@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Balbir Singh wrote: > Pavel Emelyanov wrote: >> Balbir Singh wrote: >>> This is a rewrite of a patch I had written long back to remove struct page >>> (I shared the patches with Kamezawa, but never posted them anywhere else). >>> I spent the weekend, cleaning them up for 2.6.27-rc5-mmotm (29 Aug 2008). >>> >>> I've tested the patches on an x86_64 box, I've run a simple test running >>> under the memory control group and the same test running concurrently under >>> two different groups (and creating pressure within their groups). I've also >>> compiled the patch with CGROUP_MEM_RES_CTLR turned off. >>> >>> Advantages of the patch >>> >>> 1. It removes the extra pointer in struct page >>> >>> Disadvantages >>> >>> 1. It adds an additional lock structure to struct page_cgroup >>> 2. Radix tree lookup is not an O(1) operation, once the page is known >>> getting to the page_cgroup (pc) is a little more expensive now. >> And besides, we also have a global lock, that protects even lookup >> from this structure. Won't this affect us too much on bug-smp nodes? > > Sorry, not sure I understand. The lookup is done under RCU. Updates are done > using the global lock. It should not be hard to make the radix tree per node > later (as an iterative refinement). > OOPS, indeed. Sorry for the confusion, then. :) -- 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