From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80416C433DF for ; Mon, 6 Jul 2020 16:08:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5288F20723 for ; Mon, 6 Jul 2020 16:08:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729525AbgGFQIS (ORCPT ); Mon, 6 Jul 2020 12:08:18 -0400 Received: from mga07.intel.com ([134.134.136.100]:43194 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729367AbgGFQIQ (ORCPT ); Mon, 6 Jul 2020 12:08:16 -0400 IronPort-SDR: Fq0Gl326DhhEvEwNPi7Q9mKiAFlbAcbBL6nVWsoX4GIbcsz1nZcCfVhJl3uNtrSbSltIwig42T 5tQEjryc1iUg== X-IronPort-AV: E=McAfee;i="6000,8403,9673"; a="212424256" X-IronPort-AV: E=Sophos;i="5.75,320,1589266800"; d="scan'208";a="212424256" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Jul 2020 09:08:15 -0700 IronPort-SDR: hK09vW0VonTkhD7BVOoLSdCW4JvdYOMoUpm0jfintgXtC4zW+ojUN4hpZsl+Osr/7ovFMiRFj8 fLSTzBceebiQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,320,1589266800"; d="scan'208";a="279318902" Received: from tassilo.jf.intel.com (HELO tassilo.localdomain) ([10.7.201.21]) by orsmga003.jf.intel.com with ESMTP; 06 Jul 2020 09:08:15 -0700 Received: by tassilo.localdomain (Postfix, from userid 1000) id 726CF30119A; Mon, 6 Jul 2020 09:08:15 -0700 (PDT) Date: Mon, 6 Jul 2020 09:08:15 -0700 From: Andi Kleen To: Michal Hocko Cc: Michal =?iso-8859-1?Q?Such=E1nek?= , David Hildenbrand , Gautham R Shenoy , Srikar Dronamraju , Linus Torvalds , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Satheesh Rajendran , Mel Gorman , "Kirill A. Shutemov" , Andrew Morton , linuxppc-dev@lists.ozlabs.org, Christopher Lameter , Vlastimil Babka Subject: Re: [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline Message-ID: <20200706160815.GH3448022@tassilo.jf.intel.com> References: <20200624092846.9194-4-srikar@linux.vnet.ibm.com> <20200701084200.GN2369@dhcp22.suse.cz> <20200701100442.GB17918@linux.vnet.ibm.com> <184102af-ecf2-c834-db46-173ab2e66f51@redhat.com> <20200701110145.GC17918@linux.vnet.ibm.com> <0468f965-8762-76a3-93de-3987cf859927@redhat.com> <12945273-d788-710d-e8d7-974966529c7d@redhat.com> <20200701122110.GT2369@dhcp22.suse.cz> <20200703091001.GJ21462@kitsune.suse.cz> <20200703092414.GR18446@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200703092414.GR18446@dhcp22.suse.cz> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > > What's the point of this indirection other than another way of avoiding > > empty node 0? > > Honestly, I do not have any idea. I've traced it down to > Author: Andi Kleen > Date: Tue Jan 11 15:35:48 2005 -0800 I don't remember all the details, and I can't even find the commit (is it in linux-historic?). But AFAIK there's no guarantee PXMs are small and continuous, so it seemed better to have a clean zero based space. Back then we had a lot of problems with buggy SRAT tables in BIOS, so we really tried to avoid trusting the BIOS as much as possible. -Andi