From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753945AbdGNKuJ (ORCPT ); Fri, 14 Jul 2017 06:50:09 -0400 Received: from mx2.suse.de ([195.135.220.15]:33403 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753874AbdGNKuH (ORCPT ); Fri, 14 Jul 2017 06:50:07 -0400 Date: Fri, 14 Jul 2017 12:50:04 +0200 From: Michal Hocko To: Mel Gorman Cc: linux-mm@kvack.org, Andrew Morton , Johannes Weiner , Vlastimil Babka , LKML Subject: Re: [PATCH 3/9] mm, page_alloc: do not set_cpu_numa_mem on empty nodes initialization Message-ID: <20170714105003.GE2618@dhcp22.suse.cz> References: <20170714080006.7250-1-mhocko@kernel.org> <20170714080006.7250-4-mhocko@kernel.org> <20170714094810.ftthctfz33artwh2@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170714094810.ftthctfz33artwh2@suse.de> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 14-07-17 10:48:10, Mel Gorman wrote: > On Fri, Jul 14, 2017 at 10:00:00AM +0200, Michal Hocko wrote: > > From: Michal Hocko > > > > __build_all_zonelists reinitializes each online cpu local node for > > CONFIG_HAVE_MEMORYLESS_NODES. This makes sense because previously memory > > less nodes could gain some memory during memory hotplug and so the local > > node should be changed for CPUs close to such a node. It makes less > > sense to do that unconditionally for a newly creaded NUMA node which is > > still offline and without any memory. > > > > Let's also simplify the cpu loop and use for_each_online_cpu instead of > > an explicit cpu_online check for all possible cpus. > > > > Signed-off-by: Michal Hocko > > --- > > mm/page_alloc.c | 6 ++---- > > 1 file changed, 2 insertions(+), 4 deletions(-) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 7746824a425d..ebc3311555b1 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -5096,10 +5096,8 @@ static int __build_all_zonelists(void *data) > > > > build_zonelists(pgdat); > > } > > - } > > > > #ifdef CONFIG_HAVE_MEMORYLESS_NODES > > - for_each_possible_cpu(cpu) { > > /* > > * We now know the "local memory node" for each node-- > > * i.e., the node of the first zone in the generic zonelist. > > @@ -5108,10 +5106,10 @@ static int __build_all_zonelists(void *data) > > * secondary cpus' numa_mem as they come on-line. During > > * node/memory hotplug, we'll fixup all on-line cpus. > > */ > > - if (cpu_online(cpu)) > > + for_each_online_cpu(cpu) > > set_cpu_numa_mem(cpu, local_memory_node(cpu_to_node(cpu))); > > - } > > #endif > > + } > > > > This is not as clear a benefit. For each online node, we now go through > all online CPUs once per node. There would be some rationale for using > for_each_online_cpu. I am not sure I understand. I am using for_each_online_cpu... -- Michal Hocko SUSE Labs