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 D14AFC7EE2E for ; Fri, 9 Jun 2023 09:55:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240594AbjFIJzK (ORCPT ); Fri, 9 Jun 2023 05:55:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45350 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239682AbjFIJy1 (ORCPT ); Fri, 9 Jun 2023 05:54:27 -0400 Received: from out30-101.freemail.mail.aliyun.com (out30-101.freemail.mail.aliyun.com [115.124.30.101]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD70946BB for ; Fri, 9 Jun 2023 02:46:11 -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=ay29a033018046051;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0VkhjX-o_1686303963; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0VkhjX-o_1686303963) by smtp.aliyun-inc.com; Fri, 09 Jun 2023 17:46:04 +0800 From: Baolin Wang To: akpm@linux-foundation.org Cc: mgorman@techsingularity.net, vbabka@suse.cz, david@redhat.com, baolin.wang@linux.alibaba.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] mm: compaction: skip memory hole rapidly when isolating migratable pages Date: Fri, 9 Jun 2023 17:45:54 +0800 Message-Id: <8cc668b77c8eb2fa78058b3d81386ebed9c5a9cd.1686294549.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On some machines, the normal zone can have a large memory hole like below memory layout, and we can see the range from 0x100000000 to 0x1800000000 is a hole. So when isolating some migratable pages, the scanner can meet the hole and it will take more time to skip the large hole. From my measurement, I can see the isolation scanner will take 80us ~ 100us to skip the large hole [0x100000000 - 0x1800000000]. So adding a new helper to fast search next online memory section to skip the large hole can help to find next suitable pageblock efficiently. With this patch, I can see the large hole scanning only takes < 1us. [ 0.000000] Zone ranges: [ 0.000000] DMA [mem 0x0000000040000000-0x00000000ffffffff] [ 0.000000] DMA32 empty [ 0.000000] Normal [mem 0x0000000100000000-0x0000001fa7ffffff] [ 0.000000] Movable zone start for each node [ 0.000000] Early memory node ranges [ 0.000000] node 0: [mem 0x0000000040000000-0x0000000fffffffff] [ 0.000000] node 0: [mem 0x0000001800000000-0x0000001fa3c7ffff] [ 0.000000] node 0: [mem 0x0000001fa3c80000-0x0000001fa3ffffff] [ 0.000000] node 0: [mem 0x0000001fa4000000-0x0000001fa402ffff] [ 0.000000] node 0: [mem 0x0000001fa4030000-0x0000001fa40effff] [ 0.000000] node 0: [mem 0x0000001fa40f0000-0x0000001fa73cffff] [ 0.000000] node 0: [mem 0x0000001fa73d0000-0x0000001fa745ffff] [ 0.000000] node 0: [mem 0x0000001fa7460000-0x0000001fa746ffff] [ 0.000000] node 0: [mem 0x0000001fa7470000-0x0000001fa758ffff] [ 0.000000] node 0: [mem 0x0000001fa7590000-0x0000001fa7ffffff] Signed-off-by: Baolin Wang --- include/linux/mmzone.h | 10 ++++++++++ mm/compaction.c | 23 ++++++++++++++++++++++- 2 files changed, 32 insertions(+), 1 deletion(-) diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 5a7ada0413da..87e6c535d895 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -2000,6 +2000,16 @@ static inline unsigned long next_present_section_nr(unsigned long section_nr) return -1; } +static inline unsigned long next_online_section_nr(unsigned long section_nr) +{ + while (++section_nr <= __highest_present_section_nr) { + if (online_section_nr(section_nr)) + return section_nr; + } + + return -1UL; +} + /* * These are _only_ used during initialisation, therefore they * can use __initdata ... They could have names to indicate diff --git a/mm/compaction.c b/mm/compaction.c index 3398ef3a55fe..3a55fdd20c49 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -229,6 +229,21 @@ static void reset_cached_positions(struct zone *zone) pageblock_start_pfn(zone_end_pfn(zone) - 1); } +static unsigned long skip_hole_pageblock(unsigned long start_pfn) +{ + unsigned long next_online_nr; + unsigned long start_nr = pfn_to_section_nr(start_pfn); + + if (online_section_nr(start_nr)) + return -1UL; + + next_online_nr = next_online_section_nr(start_nr); + if (next_online_nr != -1UL) + return section_nr_to_pfn(next_online_nr); + + return -1UL; +} + /* * Compound pages of >= pageblock_order should consistently be skipped until * released. It is always pointless to compact pages of such order (if they are @@ -1991,8 +2006,14 @@ static isolate_migrate_t isolate_migratepages(struct compact_control *cc) page = pageblock_pfn_to_page(block_start_pfn, block_end_pfn, cc->zone); - if (!page) + if (!page) { + unsigned long next_pfn; + + next_pfn = skip_hole_pageblock(block_start_pfn); + if (next_pfn != -1UL) + block_end_pfn = next_pfn; continue; + } /* * If isolation recently failed, do not retry. Only check the -- 2.27.0