Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754280AbaBSV4E (ORCPT ); Wed, 19 Feb 2014 16:56:04 -0500 Received: from mail-pa0-f53.google.com ([209.85.220.53]:40120 "EHLO mail-pa0-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752655AbaBSV4C (ORCPT ); Wed, 19 Feb 2014 16:56:02 -0500 Date: Wed, 19 Feb 2014 13:56:00 -0800 (PST) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Nishanth Aravamudan cc: Michal Hocko , linux-mm@kvack.org, LKML Subject: Re: [RFC PATCH] mm: exclude memory less nodes from zone_reclaim In-Reply-To: <20140219175339.GG27108@linux.vnet.ibm.com> Message-ID: References: <20140219082313.GB14783@dhcp22.suse.cz> <1392829383-4125-1-git-send-email-mhocko@suse.cz> <20140219175339.GG27108@linux.vnet.ibm.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 19 Feb 2014, Nishanth Aravamudan wrote: > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 3e953f07edb0..4a44bdc7a8cf 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1855,7 +1855,7 @@ static void __paginginit init_zone_allows_reclaim(int nid) > > { > > int i; > > > > - for_each_online_node(i) > > + for_each_node_state(i, N_HIGH_MEMORY) > > if (node_distance(nid, i) <= RECLAIM_DISTANCE) > > node_set(i, NODE_DATA(nid)->reclaim_nodes); > > else > > @@ -4901,7 +4901,8 @@ void __paginginit free_area_init_node(int nid, unsigned long *zones_size, > > > > pgdat->node_id = nid; > > pgdat->node_start_pfn = node_start_pfn; > > - init_zone_allows_reclaim(nid); > > + if (node_state(nid, N_HIGH_MEMORY)) > > + init_zone_allows_reclaim(nid); > > I'm still new to this code, but isn't this saying that if a node has no > memory, then it shouldn't reclaim from any node? But, for a memoryless > node to ensure progress later if reclaim is necessary, it *must* reclaim > from other nodes? So wouldn't we want to set reclaim_nodes() in that > case to node_states[N_MEMORY]? > The only time when pgdat->reclaim_nodes or zone_reclaim_mode matters is when iterating through a zonelist for page allocation and a memoryless node should never appear in a zonelist for page allocation, so this is just preventing setting zone_reclaim_mode unnecessarily because the only nodes with > RECLAIM_DISTANCE to another node are memoryless. So this patch is fine as long as it gets s/N_HIGH_MEMORY/N_MEMORY/. Acked-by: David Rientjes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/