Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753571AbcLGQp6 (ORCPT ); Wed, 7 Dec 2016 11:45:58 -0500 Received: from outbound-smtp08.blacknight.com ([46.22.139.13]:39285 "EHLO outbound-smtp08.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753263AbcLGQp5 (ORCPT ); Wed, 7 Dec 2016 11:45:57 -0500 Date: Wed, 7 Dec 2016 16:45:54 +0000 From: Mel Gorman To: Christoph Lameter Cc: Andrew Morton , Michal Hocko , Vlastimil Babka , Johannes Weiner , Jesper Dangaard Brouer , Joonsoo Kim , Linux-MM , Linux-Kernel Subject: Re: [PATCH] mm: page_alloc: High-order per-cpu page allocator v7 Message-ID: <20161207164554.b73qjfxy2w3h3ycr@techsingularity.net> References: <20161207101228.8128-1-mgorman@techsingularity.net> <20161207155750.yfsizliaoodks5k4@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 983 Lines: 23 On Wed, Dec 07, 2016 at 10:40:47AM -0600, Christoph Lameter wrote: > On Wed, 7 Dec 2016, Mel Gorman wrote: > > > Which is related to the fundamentals of fragmentation control in > > general. At some point there will have to be a revisit to get back to > > the type of reliability that existed in 3.0-era without the massive > > overhead it incurred. As stated before, I agree it's important but > > outside the scope of this patch. > > What reliability issues are there? 3.X kernels were better in what > way? Which overhead are we talking about? > 3.0-era kernels had better fragmentation control, higher success rates at allocation etc. I vaguely recall that it had fewer sources of high-order allocations but I don't remember specifics and part of that could be the lack of THP at the time. The overhead was massive due to massive stalls and excessive reclaim -- hours to complete some high-allocation stress tests even if the success rate was high. -- Mel Gorman SUSE Labs