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=-4.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 6446BC43444 for ; Tue, 18 Dec 2018 09:23:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3C4DF217D8 for ; Tue, 18 Dec 2018 09:23:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726498AbeLRJX6 (ORCPT ); Tue, 18 Dec 2018 04:23:58 -0500 Received: from mx2.suse.de ([195.135.220.15]:52104 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726388AbeLRJX4 (ORCPT ); Tue, 18 Dec 2018 04:23:56 -0500 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 9BBC8AD64; Tue, 18 Dec 2018 09:23:54 +0000 (UTC) Subject: Re: [PATCH 07/14] mm, compaction: Always finish scanning of a full pageblock To: Mel Gorman , Linux-MM Cc: David Rientjes , Andrea Arcangeli , Linus Torvalds , Michal Hocko , ying.huang@intel.com, kirill@shutemov.name, Andrew Morton , Linux List Kernel Mailing References: <20181214230310.572-1-mgorman@techsingularity.net> <20181214230310.572-8-mgorman@techsingularity.net> From: Vlastimil Babka Openpgp: preference=signencrypt Message-ID: Date: Tue, 18 Dec 2018 10:23:54 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.3 MIME-Version: 1.0 In-Reply-To: <20181214230310.572-8-mgorman@techsingularity.net> Content-Type: text/plain; charset=utf-8 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 12/15/18 12:03 AM, Mel Gorman wrote: > When compaction is finishing, it uses a flag to ensure the pageblock is > complete. However, in general it makes sense to always complete migration > of a pageblock. Minimally, skip information is based on a pageblock and > partially scanned pageblocks may incur more scanning in the future. The > pageblock skip handling also becomes more strict later in the series and > the hint is more useful if a complete pageblock was always scanned. > > The impact here is potentially on latencies as more scanning is done > but it's not a consistent win or loss as the scanning is not always a > high percentage of the pageblock and sometimes it is offset by future > reductions in scanning. Hence, the results are not presented this time as > it's a mix of gains/losses without any clear pattern. However, completing > scanning of the pageblock is important for later patches. > > Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka