Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754930AbaGKQTY (ORCPT ); Fri, 11 Jul 2014 12:19:24 -0400 Received: from qmta10.emeryville.ca.mail.comcast.net ([76.96.30.17]:54052 "EHLO qmta10.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754909AbaGKQTT (ORCPT ); Fri, 11 Jul 2014 12:19:19 -0400 Date: Fri, 11 Jul 2014 11:19:14 -0500 (CDT) From: Christoph Lameter To: Tejun Heo 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 In-Reply-To: <20140711160152.GC30865@htj.dyndns.org> Message-ID: 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> <20140711160152.GC30865@htj.dyndns.org> 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 Fri, 11 Jul 2014, Tejun Heo wrote: > On Fri, Jul 11, 2014 at 10:58:52AM -0500, Christoph Lameter wrote: > > > But, GFP_THISNODE + numa_mem_id() is identical to numa_node_id() + > > > nearest node with memory fallback. Is there any case where the user > > > would actually want to always fail if it's on the memless node? > > > > GFP_THISNODE allocatios must fail if there is no memory available on > > the node. No fallback allowed. > > I don't know. The intention is that the caller wants something on > this node or the caller will fail or fallback ourselves, right? For > most use cases just considering the nearest memory node as "local" for > memless nodes should work and serve the intentions of the users close > enough. Whether that'd be better or we'd be better off with something > else depends on the details for sure. Yes that works. But if we want a consistent node to allocate from (and avoid the fallbacks) then we need this patch. I think this is up to those needing memoryless nodes to figure out what semantics they need. -- 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/