From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f180.google.com (mail-pd0-f180.google.com [209.85.192.180]) by kanga.kvack.org (Postfix) with ESMTP id DFCBC6B0031 for ; Wed, 19 Feb 2014 16:56:02 -0500 (EST) Received: by mail-pd0-f180.google.com with SMTP id x10so933557pdj.11 for ; Wed, 19 Feb 2014 13:56:02 -0800 (PST) Received: from mail-pa0-x231.google.com (mail-pa0-x231.google.com [2607:f8b0:400e:c03::231]) by mx.google.com with ESMTPS id fd10si972648pad.341.2014.02.19.13.56.01 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 19 Feb 2014 13:56:02 -0800 (PST) Received: by mail-pa0-f49.google.com with SMTP id hz1so971747pad.22 for ; Wed, 19 Feb 2014 13:56:01 -0800 (PST) Date: Wed, 19 Feb 2014 13:56:00 -0800 (PST) From: David Rientjes 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> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Nishanth Aravamudan Cc: Michal Hocko , linux-mm@kvack.org, LKML 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, 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