From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ed1-f71.google.com (mail-ed1-f71.google.com [209.85.208.71]) by kanga.kvack.org (Postfix) with ESMTP id 087F76B41D5 for ; Mon, 26 Nov 2018 07:37:42 -0500 (EST) Received: by mail-ed1-f71.google.com with SMTP id s50so9044672edd.11 for ; Mon, 26 Nov 2018 04:37:41 -0800 (PST) Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id i18-v6si259666ejy.35.2018.11.26.04.37.00 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 26 Nov 2018 04:37:12 -0800 (PST) Subject: Re: [PATCH 1/5] mm, page_alloc: Spread allocations across zones before introducing fragmentation References: <20181123114528.28802-1-mgorman@techsingularity.net> <20181123114528.28802-2-mgorman@techsingularity.net> From: Vlastimil Babka Message-ID: <7a3b2706-8d8c-9233-d6fc-26ace52641e7@suse.cz> Date: Mon, 26 Nov 2018 13:36:57 +0100 MIME-Version: 1.0 In-Reply-To: <20181123114528.28802-2-mgorman@techsingularity.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman , Andrew Morton Cc: David Rientjes , Andrea Arcangeli , Zi Yan , Michal Hocko , LKML , Linux-MM On 11/23/18 12:45 PM, Mel Gorman wrote: ... > Fault latencies are slightly reduced while allocation success rates remain > at zero as this configuration does not make any special effort to allocate > THP and fio is heavily active at the time and either filling memory or > keeping pages resident. However, a 49% reduction of serious fragmentation > events reduces the changes of external fragmentation being a problem in > the future. > > Vlastimil asked during review for a breakdown of the allocation types > that are falling back. > > vanilla > 3816 MIGRATE_UNMOVABLE > 800845 MIGRATE_MOVABLE > 33 MIGRATE_UNRECLAIMABLE > > patch > 735 MIGRATE_UNMOVABLE > 408135 MIGRATE_MOVABLE > 42 MIGRATE_UNRECLAIMABLE Nit: it's MIGRATE_RECLAIMABLE :) > The majority of the fallbacks are due to movable allocations and this is > consistent for the workload throughout the series so will not be presented > again as the primary source of fallbacks are movable allocations. Note that I was more interested in the *reduction* of different kinds of fallbacks, not their ratios - that the majority is caused by movable allocations is fully expected. And the results above actually show that while the reduction for MOVABLE is ~50%, the reduction for UNMOVABLE is actually 80%! IMHO that's great (better than I would expect, in fact), and good to know. ... > Overall, the patch reduces the number of external fragmentation causing > events so the success of THP over long periods of time would be improved > for this adverse workload. > > Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka