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_PASS 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 E3A72ECDE39 for ; Wed, 17 Oct 2018 17:06:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8A59321476 for ; Wed, 17 Oct 2018 17:06:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8A59321476 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728007AbeJRBCw (ORCPT ); Wed, 17 Oct 2018 21:02:52 -0400 Received: from mx2.suse.de ([195.135.220.15]:53312 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727678AbeJRBCw (ORCPT ); Wed, 17 Oct 2018 21:02:52 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 36CBFAE14; Wed, 17 Oct 2018 17:06:14 +0000 (UTC) Subject: Re: [RFC v4 PATCH 2/5] mm/__free_one_page: skip merge for order-0 page unless compaction failed To: Mel Gorman , Aaron Lu Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Huang Ying , Dave Hansen , Kemi Wang , Tim Chen , Andi Kleen , Michal Hocko , Matthew Wilcox , Daniel Jordan , Tariq Toukan , Jesper Dangaard Brouer References: <20181017063330.15384-1-aaron.lu@intel.com> <20181017063330.15384-3-aaron.lu@intel.com> <20181017104427.GJ5819@techsingularity.net> <20181017131059.GA9167@intel.com> <20181017135807.GL5819@techsingularity.net> From: Vlastimil Babka Openpgp: preference=signencrypt Autocrypt: addr=vbabka@suse.cz; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181017135807.GL5819@techsingularity.net> Content-Type: text/plain; charset=US-ASCII Content-Language: en-US Content-Transfer-Encoding: 7BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/17/18 3:58 PM, Mel Gorman wrote: > Again, as compaction is not guaranteed to find the pageblocks, it would > be important to consider whether a) that matters or b) find an > alternative way of keeping unmerged buddies on separate lists so they > can be quickly discovered when a high-order allocation fails. Agree, unmerged buddies could be on separate freelist from regular order-0 freelist. That list could be also preferred to allocations before the regular one. Then one could e.g. try "direct merging" via this list when compaction fails, or prefer direct merging to compaction for non-costly-order allocations, do direct merging when allocation context doesn't even allow compaction (atomic etc). Also I would definitely consider always merging pages freed to non-MOVABLE pageblocks. We really don't want to increase the fragmentation in those. However that means it probably won't help the netperf case? Vlastimil