Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754230AbaGKPWD (ORCPT ); Fri, 11 Jul 2014 11:22:03 -0400 Received: from mail-qc0-f177.google.com ([209.85.216.177]:61361 "EHLO mail-qc0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751459AbaGKPWB (ORCPT ); Fri, 11 Jul 2014 11:22:01 -0400 Date: Fri, 11 Jul 2014 11:21:56 -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: <20140711152156.GB29137@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> 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 Hello, On Fri, Jul 11, 2014 at 10:13:57AM -0500, Christoph Lameter wrote: > Allocators typically fall back but they wont in some cases if you say > that you want memory from a particular node. A GFP_THISNODE would force a > failure of the alloc. In other cases it should fall back. I am not sure > that all allocations obey these conventions though. 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? Even if that's the case, there's no reason to burden everyone with this distinction. Most users just wanna say "I'm on this node. Please allocate considering that". There's nothing wrong with using numa_node_id() for that. 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/