Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751852AbbHTAC5 (ORCPT ); Wed, 19 Aug 2015 20:02:57 -0400 Received: from mail-pa0-f54.google.com ([209.85.220.54]:35060 "EHLO mail-pa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751015AbbHTAC4 (ORCPT ); Wed, 19 Aug 2015 20:02:56 -0400 Date: Wed, 19 Aug 2015 17:02:54 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Jiang Liu cc: Andrew Morton , Mel Gorman , Mike Galbraith , Peter Zijlstra , "Rafael J . Wysocki" , Tang Chen , Tejun Heo , Cliff Whickman , Robin Holt , Tony Luck , linux-mm@kvack.org, linux-hotplug@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org Subject: Re: [Patch V3 3/9] sgi-xp: Replace cpu_to_node() with cpu_to_mem() to support memoryless node In-Reply-To: <55D43C63.7060802@linux.intel.com> Message-ID: References: <1439781546-7217-1-git-send-email-jiang.liu@linux.intel.com> <1439781546-7217-4-git-send-email-jiang.liu@linux.intel.com> <55D43C63.7060802@linux.intel.com> User-Agent: Alpine 2.10 (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 Content-Length: 1338 Lines: 28 On Wed, 19 Aug 2015, Jiang Liu wrote: > > Why not simply fix build_zonelists_node() so that the __GFP_THISNODE > > zonelists are set up to reference the zones of cpu_to_mem() for memoryless > > nodes? > > > > It seems much better than checking and maintaining every __GFP_THISNODE > > user to determine if they are using a memoryless node or not. I don't > > feel that this solution is maintainable in the longterm. > Hi David, > There are some usage cases, such as memory migration, > expect the page allocator rejecting memory allocation requests > if there is no memory on local node. So we have: > 1) alloc_pages_node(cpu_to_node(), __GFP_THISNODE) to only allocate > memory from local node. > 2) alloc_pages_node(cpu_to_mem(), __GFP_THISNODE) to allocate memory > from local node or from nearest node if local node is memoryless. > Right, so do you think it would be better to make the default zonelists be setup so that cpu_to_node()->zonelists == cpu_to_mem()->zonelists and then individual callers that want to fail for memoryless nodes check populated_zone() themselves? -- 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/