From nobody Thu Feb 12 06:13:08 2026 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 591A9C7618E for ; Wed, 26 Apr 2023 15:03:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241215AbjDZPDb (ORCPT ); Wed, 26 Apr 2023 11:03:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240651AbjDZPD3 (ORCPT ); Wed, 26 Apr 2023 11:03:29 -0400 Received: from out30-131.freemail.mail.aliyun.com (out30-131.freemail.mail.aliyun.com [115.124.30.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8BB345279 for ; Wed, 26 Apr 2023 08:03:27 -0700 (PDT) X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046049;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0Vh3nnLS_1682521402; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0Vh3nnLS_1682521402) by smtp.aliyun-inc.com; Wed, 26 Apr 2023 23:03:23 +0800 From: Baolin Wang To: akpm@linux-foundation.org Cc: mgorman@techsingularity.net, vbabka@suse.cz, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] Revert "Revert "mm/compaction: fix set skip in fast_find_migrateblock"" Date: Wed, 26 Apr 2023 23:03:13 +0800 Message-Id: <3576e3520c044beb2a81860aecb2d4f597089300.1682521303.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 we should revert the temporary fix by commit 95e7a450b819, since the fast pfn found by fast_find_migrateblock() really can help to isolate some migratable pages. After reverting the commit, the regression has gone. v6.2-rc1 v6.3 v6.= 3_patched Percentage huge-3 81.35 ( 0.00%) 32.97 ( -59.47%) 87.7= 8 ( 7.90%) Percentage huge-5 89.92 ( 0.00%) 41.70 ( -53.63%) 89.6= 8 ( -0.27%) Percentage huge-7 92.41 ( 0.00%) 34.08 ( -63.12%) 85.8= 9 ( -7.05%) Percentage huge-12 90.29 ( 0.00%) 41.10 ( -54.49%) 94.1= 0 ( 4.22%) Percentage huge-18 82.38 ( 0.00%) 41.24 ( -49.95%) 85.0= 6 ( 3.25%) Percentage huge-24 80.34 ( 0.00%) 35.99 ( -55.20%) 84.3= 8 ( 5.02%) Percentage huge-30 88.90 ( 0.00%) 44.20 ( -50.28%) 95.5= 4 ( 7.48%) Percentage huge-32 90.69 ( 0.00%) 79.57 ( -12.25%) 92.3= 0 ( 1.78%) Signed-off-by: Baolin Wang --- mm/compaction.c | 1 - 1 file changed, 1 deletion(-) diff --git a/mm/compaction.c b/mm/compaction.c index 33650541bebc..567c8d41d01e 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1860,7 +1860,6 @@ static unsigned long fast_find_migrateblock(struct co= mpact_control *cc) pfn =3D cc->zone->zone_start_pfn; cc->fast_search_fail =3D 0; found_block =3D true; - set_pageblock_skip(freepage); break; } } --=20 2.27.0