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=-10.4 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E58F2C433E0 for ; Mon, 18 Jan 2021 17:41:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5FD1122CA1 for ; Mon, 18 Jan 2021 17:41:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5FD1122CA1 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 8905B6B0256; Mon, 18 Jan 2021 12:41:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 841628D0020; Mon, 18 Jan 2021 12:41:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7563D8D0017; Mon, 18 Jan 2021 12:41:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0147.hostedemail.com [216.40.44.147]) by kanga.kvack.org (Postfix) with ESMTP id 5FA7B6B0256 for ; Mon, 18 Jan 2021 12:41:17 -0500 (EST) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 259771EE6 for ; Mon, 18 Jan 2021 17:41:17 +0000 (UTC) X-FDA: 77719612194.14.lock18_1f0a0112754b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id E0A131822987B for ; Mon, 18 Jan 2021 17:41:16 +0000 (UTC) X-HE-Tag: lock18_1f0a0112754b X-Filterd-Recvd-Size: 5208 Received: from smtprelay.hostedemail.com (smtprelay0144.hostedemail.com [216.40.44.144]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Mon, 18 Jan 2021 17:41:16 +0000 (UTC) Received: from forelay.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay03.hostedemail.com (Postfix) with ESMTP id D9796837F27E for ; Mon, 18 Jan 2021 17:41:15 +0000 (UTC) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id BC4F5824999B for ; Mon, 18 Jan 2021 17:41:15 +0000 (UTC) X-FDA: 77719612110.09.river39_3d076d72754b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin09.hostedemail.com (Postfix) with ESMTP id A0F10180AD830 for ; Mon, 18 Jan 2021 17:41:15 +0000 (UTC) X-HE-Tag: river39_3d076d72754b X-Filterd-Recvd-Size: 3783 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Mon, 18 Jan 2021 17:41:15 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 96710AFEF; Mon, 18 Jan 2021 17:41:13 +0000 (UTC) Subject: Re: [PATCH V3] mm/compaction: correct deferral logic for proactive compaction To: Charan Teja Reddy , akpm@linux-foundation.org, mhocko@suse.com, khalid.aziz@oracle.com, ngupta@nitingupta.dev, vinmenon@codeaurora.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1610989938-31374-1-git-send-email-charante@codeaurora.org> From: Vlastimil Babka Message-ID: Date: Mon, 18 Jan 2021 18:41:13 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <1610989938-31374-1-git-send-email-charante@codeaurora.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 1/18/21 6:12 PM, Charan Teja Reddy wrote: > should_proactive_compact_node() returns true when sum of the > weighted fragmentation score of all the zones in the node is greater > than the wmark_high of compaction, which then triggers the proactive > compaction that operates on the individual zones of the node. But > proactive compaction runs on the zone only when its weighted > fragmentation score is greater than wmark_low(=wmark_high - 10). > > This means that the sum of the weighted fragmentation scores of all the > zones can exceed the wmark_high but individual weighted fragmentation > zone scores can still be less than wmark_low which makes the unnecessary > trigger of the proactive compaction only to return doing nothing. > > Issue with the return of proactive compaction with out even trying is > its deferral. It is simply deferred for 1 << COMPACT_MAX_DEFER_SHIFT if > the scores across the proactive compaction is same, thinking that > compaction didn't make any progress but in reality it didn't even try. > With the delay between successive retries for proactive compaction is > 500msec, it can result into the deferral for ~30sec with out even trying > the proactive compaction. > > Test scenario is that: compaction_proactiveness=50 thus the wmark_low = > 50 and wmark_high = 60. System have 2 zones(Normal and Movable) with > sizes 5GB and 6GB respectively. After opening some apps on the android, > the weighted fragmentation scores of these zones are 47 and 49 > respectively. Since the sum of these fragmentation scores are above the > wmark_high which triggers the proactive compaction and there since the > individual zones weighted fragmentation scores are below wmark_low, it > returns without trying the proactive compaction. As a result the > weighted fragmentation scores of the zones are still 47 and 49 which > makes the existing logic to defer the compaction thinking that > noprogress is made across the compaction. > > Fix this by checking just zone fragmentation score, not the weighted, in > __compact_finished() and use the zones weighted fragmentation score in > fragmentation_score_node(). In the test case above, If the weighted > average of is above wmark_high, then individual score (not adjusted) of > atleast one zone has to be above wmark_high. Thus it avoids the > unnecessary trigger and deferrals of the proactive compaction. > > Fix-suggested-by: Vlastimil Babka > Signed-off-by: Charan Teja Reddy Acked-by: Vlastimil Babka Thanks!