From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3FC383CF71 for ; Mon, 22 Jan 2024 13:02:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705928533; cv=none; b=NmDw/ivEKT7l+xL/BFDKgRTSmZxRMKnGXPLEog0M48hWoASCftc0DEwn1TCOhoUHW/zf7ibxs4MnBGGFeNgmUjR6QAQZoT+Z4MLK/LhsnbvvfqFuWVG2PGOrgMJVPrcj8kXPZxd0CwQeIhfGpKS2R5F1EG43uFh3NwmtUv2N3nU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705928533; c=relaxed/simple; bh=LNMEtRYYUEvztr0JZHEpSPlZZtxTJHJcYCyjncWD5/I=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=kqIdqUADog/2OJvHeyIlA6wZG0QGz6Y9mCXFX4xR36jYTfRIpHKCoLx+bMyhD19HdbH4dkcnl6jHihtBey5EZqm8K2vtAnE8X6FPkr8K+1+tHpN34h1UHjXbhXzLU7dFhS/lvzhxUZ9SdJ1qliqUfStXoQYeeCG6lOF9wtOCh+k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; arc=none smtp.client-ip=115.124.30.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com X-Alimail-AntiSpam:AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018045170;MF=baolin.wang@linux.alibaba.com;NM=1;PH=DS;RN=6;SR=0;TI=SMTPD_---0W.9DBpR_1705928524; Received: from localhost(mailfrom:baolin.wang@linux.alibaba.com fp:SMTPD_---0W.9DBpR_1705928524) by smtp.aliyun-inc.com; Mon, 22 Jan 2024 21:02:05 +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 2/2] mm: compaction: update the cc->nr_migratepages when allocating or freeing the freepages Date: Mon, 22 Jan 2024 21:01:54 +0800 Message-Id: <0773058df022fa701b78f9a6dfe3c501a1a77351.1705928395.git.baolin.wang@linux.alibaba.com> X-Mailer: git-send-email 2.39.3 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Currently we will use 'cc->nr_freepages >= cc->nr_migratepages' comparison to ensure that enough freepages are isolated in isolate_freepages(), however it just decreases the cc->nr_freepages without updating cc->nr_migratepages in compaction_alloc(), which will waste more CPU cycles and cause too many freepages to be isolated. So we should also update the cc->nr_migratepages when allocating or freeing the freepages to avoid isolating excess freepages. And I can see fewer free pages are scanned and isolated when running thpcompact on my Arm64 server: k6.7 k6.7_patched Ops Compaction pages isolated 120692036.00 118160797.00 Ops Compaction migrate scanned 131210329.00 154093268.00 Ops Compaction free scanned 1090587971.00 1080632536.00 Ops Compact scan efficiency 12.03 14.26 Moreover, I did not see an obvious latency improvements, this is likely because isolating freepages is not the bottleneck in the thpcompact test case. k6.7 k6.7_patched Amean fault-both-1 1089.76 ( 0.00%) 1080.16 * 0.88%* Amean fault-both-3 1616.48 ( 0.00%) 1636.65 * -1.25%* Amean fault-both-5 2266.66 ( 0.00%) 2219.20 * 2.09%* Amean fault-both-7 2909.84 ( 0.00%) 2801.90 * 3.71%* Amean fault-both-12 4861.26 ( 0.00%) 4733.25 * 2.63%* Amean fault-both-18 7351.11 ( 0.00%) 6950.51 * 5.45%* Amean fault-both-24 9059.30 ( 0.00%) 9159.99 * -1.11%* Amean fault-both-30 10685.68 ( 0.00%) 11399.02 * -6.68%* Signed-off-by: Baolin Wang --- mm/compaction.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/compaction.c b/mm/compaction.c index 066b72b3471a..6c84e3a5b32b 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1779,6 +1779,7 @@ static struct folio *compaction_alloc(struct folio *src, unsigned long data) dst = list_entry(cc->freepages.next, struct folio, lru); list_del(&dst->lru); cc->nr_freepages--; + cc->nr_migratepages--; return dst; } @@ -1794,6 +1795,7 @@ static void compaction_free(struct folio *dst, unsigned long data) list_add(&dst->lru, &cc->freepages); cc->nr_freepages++; + cc->nr_migratepages++; } /* possible outcome of isolate_migratepages */ -- 2.39.3