From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sd0109e.au.ibm.com (d23rh905.au.ibm.com [202.81.18.225]) by e23smtp04.au.ibm.com (8.13.1/8.13.1) with ESMTP id m894IjGM016112 for ; Tue, 9 Sep 2008 14:18:45 +1000 Received: from d23av04.au.ibm.com (d23av04.au.ibm.com [9.190.235.139]) by sd0109e.au.ibm.com (8.13.8/8.13.8/NCO v9.0) with ESMTP id m894JewP194406 for ; Tue, 9 Sep 2008 14:19:54 +1000 Received: from d23av04.au.ibm.com (loopback [127.0.0.1]) by d23av04.au.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id m894JdMG014254 for ; Tue, 9 Sep 2008 14:19:40 +1000 Message-ID: <48C5F91D.5070500@linux.vnet.ibm.com> Date: Mon, 08 Sep 2008 21:18:37 -0700 From: Balbir Singh Reply-To: balbir@linux.vnet.ibm.com MIME-Version: 1.0 Subject: Re: [RFC][PATCH] Remove cgroup member from struct page References: <20080901161927.a1fe5afc.kamezawa.hiroyu@jp.fujitsu.com> <200809011743.42658.nickpiggin@yahoo.com.au> <48BD0641.4040705@linux.vnet.ibm.com> <20080902190256.1375f593.kamezawa.hiroyu@jp.fujitsu.com> <48BD0E4A.5040502@linux.vnet.ibm.com> <20080902190723.841841f0.kamezawa.hiroyu@jp.fujitsu.com> <48BD119B.8020605@linux.vnet.ibm.com> <20080902195717.224b0822.kamezawa.hiroyu@jp.fujitsu.com> <48BD337E.40001@linux.vnet.ibm.com> <20080903123306.316beb9d.kamezawa.hiroyu@jp.fujitsu.com> <20080908152810.GA12065@balbir.in.ibm.com> <20080909125751.37042345.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20080909125751.37042345.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: KAMEZAWA Hiroyuki Cc: Nick Piggin , Andrew Morton , hugh@veritas.com, menage@google.com, xemul@openvz.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: KAMEZAWA Hiroyuki wrote: > On Mon, 8 Sep 2008 20:58:10 +0530 > Balbir Singh wrote: >> Sorry for the delay in sending out the new patch, I am traveling and >> thus a little less responsive. Here is the update patch >> >> > Hmm.. I've considered this approach for a while and my answer is that > this is not what you really want. > > Because you just moves the placement of pointer from memmap to > radix_tree both in GFP_KERNEL, total kernel memory usage is not changed. Agreed, but we do reduce the sizeof(struct page) without adding on to page_cgroup's size. So why don't we want this? > So, at least, you have to add some address calculation (as I did in March) > to getting address of page_cgroup. What address calculation do we need, sorry I don't recollect it. But page_cgroup itself consumes 32bytes > per page. Then..... > > My proposal to 32bit system is following > - remove page_cgroup completely. > - As a result, there is no per-cgroup lru. But it will not be bad > bacause the number of cgroups and pages are not big. > just a trade-off between kernel-memory-space v.s. speed. 32 bit systems with PAE can support quite a lot of memory, so I am not sure I agree. I don't like this approach > - Removing page_cgroup and just remember address of mem_cgroup per page. > This is on top of the suggested approach above? > How do you think ? > I don't like the approach. -- Balbir -- 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