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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05455C77B60 for ; Thu, 27 Apr 2023 00:58:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242720AbjD0A6H (ORCPT ); Wed, 26 Apr 2023 20:58:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36170 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242674AbjD0A6F (ORCPT ); Wed, 26 Apr 2023 20:58:05 -0400 Received: from out30-110.freemail.mail.aliyun.com (out30-110.freemail.mail.aliyun.com [115.124.30.110]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 339A93A92 for ; Wed, 26 Apr 2023 17:58:03 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R311e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046056;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=5;SR=0;TI=SMTPD_---0Vh5A7WK_1682557079; Received: from 30.97.48.53(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Vh5A7WK_1682557079) by smtp.aliyun-inc.com; Thu, 27 Apr 2023 08:58:00 +0800 Message-ID: <40db45ab-774d-4a27-a604-a56c8447969b@linux.alibaba.com> Date: Thu, 27 Apr 2023 08:57:58 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 Subject: Re: [PATCH] Revert "Revert "mm/compaction: fix set skip in fast_find_migrateblock"" To: Mel Gorman , Vlastimil Babka Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <3576e3520c044beb2a81860aecb2d4f597089300.1682521303.git.baolin.wang@linux.alibaba.com> <20230426153331.dfqagb47i4xo3ouv@techsingularity.net> From: Baolin Wang In-Reply-To: <20230426153331.dfqagb47i4xo3ouv@techsingularity.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/26/2023 11:33 PM, Mel Gorman wrote: > On Wed, Apr 26, 2023 at 05:10:14PM +0200, Vlastimil Babka wrote: >> On 4/26/23 17:03, Baolin Wang wrote: >>> This reverts commit 95e7a450b8190673675836bfef236262ceff084a. >>> >>> When I tested thpscale with v6.3 kernel, I found the compaction efficiency >>> had a great regression compared to v6.2-rc1 kernel. See below numbers: >>> v6.2-rc v6.3 >>> Percentage huge-3 81.35 ( 0.00%) 32.97 ( -59.47%) >>> Percentage huge-5 89.92 ( 0.00%) 41.70 ( -53.63%) >>> Percentage huge-7 92.41 ( 0.00%) 34.08 ( -63.12%) >>> Percentage huge-12 90.29 ( 0.00%) 41.10 ( -54.49%) >>> Percentage huge-18 82.38 ( 0.00%) 41.24 ( -49.95%) >>> Percentage huge-24 80.34 ( 0.00%) 35.99 ( -55.20%) >>> Percentage huge-30 88.90 ( 0.00%) 44.20 ( -50.28%) >>> Percentage huge-32 90.69 ( 0.00%) 79.57 ( -12.25%) >>> >>> Ops Compaction stalls 113790.00 207099.00 >>> Ops Compaction success 33983.00 19488.00 >>> Ops Compaction failures 79807.00 187611.00 >>> Ops Compaction efficiency 29.86 9.41 >>> >>> After some investigation, I found the commit 95e7a450b819 >>> ("Revert mm/compaction: fix set skip in fast_find_migrateblock") caused >>> the regression. This commit revert the commit 7efc3b726103 ("mm/compaction: >>> fix set skip in fast_find_migrateblock") to fix a CPU stalling issue, which >>> is caused by compaction stucked in repeating fast_find_migrateblock(). >>> >>> And now the compaction stalling issue is addressed by commit cfccd2e63e7e >>> ("mm, compaction: finish pageblocks on complete migration failure"). So >> >> IIRC at that time I was pointing out some scenarios that could make the >> problem appear even after that commit, and we wanted to revisit that >> when Mel is back. Ah, I missed that, and will check previous discussion. > Yes, I've prototyped the fix against 6.3-rc7 and the revert is at the > end but the revert on its own has the potential for causing problems. The > series needs to be rebased, retested and posted. What I last tested > should show up shortly at > > https://git.kernel.org/pub/scm/linux/kernel/git/mel/linux.git/ mm-follupfastmigrate-v1r1 Thanks.