From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f171.google.com (mail-ob0-f171.google.com [209.85.214.171]) by kanga.kvack.org (Postfix) with ESMTP id 3C4066B0035 for ; Wed, 19 Feb 2014 18:06:09 -0500 (EST) Received: by mail-ob0-f171.google.com with SMTP id vb8so902169obc.16 for ; Wed, 19 Feb 2014 15:06:08 -0800 (PST) Received: from e36.co.us.ibm.com (e36.co.us.ibm.com. [32.97.110.154]) by mx.google.com with ESMTPS id sp3si1729931obb.30.2014.02.19.15.06.08 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 19 Feb 2014 15:06:08 -0800 (PST) Received: from /spool/local by e36.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 19 Feb 2014 16:06:08 -0700 Received: from b03cxnp07028.gho.boulder.ibm.com (b03cxnp07028.gho.boulder.ibm.com [9.17.130.15]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 92D1A19D8042 for ; Wed, 19 Feb 2014 16:06:03 -0700 (MST) Received: from d03av01.boulder.ibm.com (d03av01.boulder.ibm.com [9.17.195.167]) by b03cxnp07028.gho.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s1JN5YJP9699648 for ; Thu, 20 Feb 2014 00:05:34 +0100 Received: from d03av01.boulder.ibm.com (localhost [127.0.0.1]) by d03av01.boulder.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s1JN64hl012068 for ; Wed, 19 Feb 2014 16:06:04 -0700 Date: Wed, 19 Feb 2014 15:05:58 -0800 From: Nishanth Aravamudan Subject: Re: [RFC PATCH] mm: exclude memory less nodes from zone_reclaim Message-ID: <20140219230558.GA28062@linux.vnet.ibm.com> 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 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Michal Hocko , linux-mm@kvack.org, LKML On 19.02.2014 [13:56:00 -0800], David Rientjes wrote: > 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/. Ah yes, sorry, I've been looking at this code perhaps too much and going a bit cross-eyed! I wonder if we should also put some comments in? But Acked-by: Nishanth Aravamudan Tested-by: Nishanth Aravamudan Thanks, Nish -- 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