Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754465AbaGKP6o (ORCPT ); Fri, 11 Jul 2014 11:58:44 -0400 Received: from mail-qg0-f42.google.com ([209.85.192.42]:40813 "EHLO mail-qg0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750998AbaGKP6m (ORCPT ); Fri, 11 Jul 2014 11:58:42 -0400 Date: Fri, 11 Jul 2014 11:58:38 -0400 From: Tejun Heo To: Christoph Lameter Cc: Jiang Liu , Andrew Morton , Mel Gorman , David Rientjes , Mike Galbraith , Peter Zijlstra , "Rafael J . Wysocki" , Vladimir Davydov , Johannes Weiner , "Kirill A. Shutemov" , Rik van Riel , Wanpeng Li , Zhang Yanfei , Catalin Marinas , Jianyu Zhan , malc , Joonsoo Kim , Fabian Frederick , Tony Luck , linux-mm@kvack.org, linux-hotplug@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC Patch V1 07/30] mm: Use cpu_to_mem()/numa_mem_id() to support memoryless node Message-ID: <20140711155838.GB30865@htj.dyndns.org> References: <1405064267-11678-1-git-send-email-jiang.liu@linux.intel.com> <1405064267-11678-8-git-send-email-jiang.liu@linux.intel.com> <20140711144205.GA27706@htj.dyndns.org> <20140711152156.GB29137@htj.dyndns.org> <20140711153302.GA30865@htj.dyndns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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, Jul 11, 2014 at 10:55:59AM -0500, Christoph Lameter wrote: > > Where X is the memless node. num_mem_id() on X would return either B > > or C, right? If B or C can't satisfy the allocation, the allocator > > would fallback to A from B and D for C, both of which aren't optimal. > > It should first fall back to C or B respectively, which the allocator > > can't do anymoe because the information is lost when the caller side > > performs numa_mem_id(). > > True but the advantage is that the numa_mem_id() allows the use of a > consitent sort of "local" node which increases allocator performance due > to the abillity to cache objects from that node. But the allocator can do the mapping the same. I really don't see why we'd push the distinction to the individual users. Thanks. -- tejun -- 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/