From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754815AbbINNFR (ORCPT ); Mon, 14 Sep 2015 09:05:17 -0400 Received: from e23smtp08.au.ibm.com ([202.81.31.141]:44185 "EHLO e23smtp08.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751901AbbINNFO (ORCPT ); Mon, 14 Sep 2015 09:05:14 -0400 X-Helo: d23dlp01.au.ibm.com X-MailFrom: raghavendra.kt@linux.vnet.ibm.com X-RcptTo: linux-kernel@vger.kernel.org Message-ID: <55F6C637.6080807@linux.vnet.ibm.com> Date: Mon, 14 Sep 2015 18:35:59 +0530 From: Raghavendra K T Organization: IBM User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130625 Thunderbird/17.0.7 MIME-Version: 1.0 To: Vladimir Davydov CC: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, anton@samba.org, akpm@linux-foundation.org, nacc@linux.vnet.ibm.com, gkurz@linux.vnet.ibm.com, zhong@linux.vnet.ibm.com, grant.likely@linaro.org, nikunj@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 1/2] mm: Replace nr_node_ids for loop with for_each_node in list lru References: <1441737107-23103-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com> <1441737107-23103-2-git-send-email-raghavendra.kt@linux.vnet.ibm.com> <20150914090010.GB30743@esperanza> <55F6B1F3.1010702@linux.vnet.ibm.com> <20150914120455.GD30743@esperanza> In-Reply-To: <20150914120455.GD30743@esperanza> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15091413-0029-0000-0000-00000229EA96 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/14/2015 05:34 PM, Vladimir Davydov wrote: > On Mon, Sep 14, 2015 at 05:09:31PM +0530, Raghavendra K T wrote: >> On 09/14/2015 02:30 PM, Vladimir Davydov wrote: >>> On Wed, Sep 09, 2015 at 12:01:46AM +0530, Raghavendra K T wrote: >>>> The functions used in the patch are in slowpath, which gets called >>>> whenever alloc_super is called during mounts. >>>> >>>> Though this should not make difference for the architectures with >>>> sequential numa node ids, for the powerpc which can potentially have >>>> sparse node ids (for e.g., 4 node system having numa ids, 0,1,16,17 >>>> is common), this patch saves some unnecessary allocations for >>>> non existing numa nodes. >>>> >>>> Even without that saving, perhaps patch makes code more readable. >>> >>> Do I understand correctly that node 0 must always be in >>> node_possible_map? I ask, because we currently test >>> lru->node[0].memcg_lrus to determine if the list is memcg aware. >>> >> >> Yes, node 0 is always there. So it should not be a problem. > > I think it should be mentioned in the comment to list_lru_memcg_aware > then. > Something like this: ? static inline bool list_lru_memcg_aware(struct list_lru *lru) { /* * This needs node 0 to be always present, even * in the systems supporting sparse numa ids. */ return !!lru->node[0].memcg_lrus; }