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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 E2DAAC282E3 for ; Sun, 21 Apr 2019 21:16:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B45D62147C for ; Sun, 21 Apr 2019 21:16:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726622AbfDUVQI (ORCPT ); Sun, 21 Apr 2019 17:16:08 -0400 Received: from outbound-smtp14.blacknight.com ([46.22.139.231]:37764 "EHLO outbound-smtp14.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725872AbfDUVQI (ORCPT ); Sun, 21 Apr 2019 17:16:08 -0400 Received: from mail.blacknight.com (unknown [81.17.254.16]) by outbound-smtp14.blacknight.com (Postfix) with ESMTPS id 5024C1C3636 for ; Sun, 21 Apr 2019 22:16:06 +0100 (IST) Received: (qmail 12317 invoked from network); 21 Apr 2019 21:16:06 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[37.228.225.79]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 21 Apr 2019 21:16:06 -0000 Date: Sun, 21 Apr 2019 22:16:04 +0100 From: Mel Gorman To: Matthew Wilcox Cc: Mike Rapoport , Andrew Morton , Mikulas Patocka , James Bottomley , linux-parisc@vger.kernel.org, linux-mm@kvack.org, Vlastimil Babka , LKML , linux-arch@vger.kernel.org Subject: Re: DISCONTIGMEM is deprecated Message-ID: <20190421211604.GN18914@techsingularity.net> References: <20190419094335.GJ18914@techsingularity.net> <20190419140521.GI7751@bombadil.infradead.org> <20190421063859.GA19926@rapoport-lnx> <20190421132606.GJ7751@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20190421132606.GJ7751@bombadil.infradead.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Apr 21, 2019 at 06:26:07AM -0700, Matthew Wilcox wrote: > On Sun, Apr 21, 2019 at 09:38:59AM +0300, Mike Rapoport wrote: > > On Fri, Apr 19, 2019 at 07:05:21AM -0700, Matthew Wilcox wrote: > > > On Fri, Apr 19, 2019 at 10:43:35AM +0100, Mel Gorman wrote: > > > > DISCONTIG is essentially deprecated and even parisc plans to move to > > > > SPARSEMEM so there is no need to be fancy, this patch simply disables > > > > watermark boosting by default on DISCONTIGMEM. > > > > > > I don't think parisc is the only arch which uses DISCONTIGMEM for !NUMA > > > scenarios. Grepping the arch/ directories shows: > > > > > > alpha (does support NUMA, but also non-NUMA DISCONTIGMEM) > > > arc (for supporting more than 1GB of memory) > > > ia64 (looks complicated ...) > > > m68k (for multiple chunks of memory) > > > mips (does support NUMA but also non-NUMA) > > > parisc (both NUMA and non-NUMA) > > > > i386 NUMA as well > > I clearly over-trimmed. The original assumption that Mel had was that > DISCONTIGMEM => NUMA, and that's not true on the above six architectures. > It is true on i386 ;-) 32-bit NUMA systems should be non-existent in practice. The last NUMA system I'm aware of that was both NUMA and 32-bit only died somewhere between 2004 and 2007. If someone is running a 64-bit capable system in 32-bit mode with NUMA, they really are just punishing themselves for fun. -- Mel Gorman SUSE Labs