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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 16514C433FE for ; Wed, 12 Oct 2022 22:52:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3F3756B0071; Wed, 12 Oct 2022 18:52:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3A3076B0073; Wed, 12 Oct 2022 18:52:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 21D1C6B0075; Wed, 12 Oct 2022 18:52:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 0C6896B0071 for ; Wed, 12 Oct 2022 18:52:00 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id C470CA044F for ; Wed, 12 Oct 2022 22:51:59 +0000 (UTC) X-FDA: 80013796758.08.D70A0EF Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by imf19.hostedemail.com (Postfix) with ESMTP id 53C3B1A0027 for ; Wed, 12 Oct 2022 22:51:59 +0000 (UTC) Received: from pps.filterd (m0044012.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 29CGZVxt001040 for ; Wed, 12 Oct 2022 15:51:58 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding : content-type; s=facebook; bh=hgWyWD/cwUh5/lYbCI2afAXdr5jSlV2ej5AgW4HRtJY=; b=qKu73sMdFW+GX4YTiefxkauMaiwFUKcib37RyDAHbknZanZ9dWKazk5vBr0ylkDvLu7J Sn44vdfLyTi5MZpUWlx1RLe1Wny85P2SDamI4mHK15zjkXUxYa3oWhpWHZ1nUi+ThZwU p5dqqq4DhOKBIJfdqQPV7bJ9phMu9R/SvLY= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3k5qdcfpu4-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Wed, 12 Oct 2022 15:51:58 -0700 Received: from twshared26370.03.ash8.facebook.com (2620:10d:c085:208::11) by mail.thefacebook.com (2620:10d:c085:21d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Wed, 12 Oct 2022 15:51:57 -0700 Received: by devvm6390.atn0.facebook.com (Postfix, from userid 352741) id 912EE4E48CDF; Wed, 12 Oct 2022 15:51:49 -0700 (PDT) From: To: , CC: , , , Alexander Zhu Subject: [PATCH v3 0/3] THP Shrinker Date: Wed, 12 Oct 2022 15:51:44 -0700 Message-ID: X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-GUID: NPXYk6492zciSnOIZ4_iNKct085_dXu9 X-Proofpoint-ORIG-GUID: NPXYk6492zciSnOIZ4_iNKct085_dXu9 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.545,FMLib:17.11.122.1 definitions=2022-10-12_11,2022-10-12_01,2022-06-22_01 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665615119; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding:in-reply-to: references:dkim-signature; bh=hgWyWD/cwUh5/lYbCI2afAXdr5jSlV2ej5AgW4HRtJY=; b=O9NGoZJB7uZTyMmMZ/zQZ3Cv5LxjO3SkMVsANbBeeDUvNR0EjsHfNQRf1UyRV3U0X55gWM qbnGOt+08omw/unh3iWqynkELzKws0ZRsVgR7eD0FT9ECDGt/AZplFumQKYe8n+JzMHpfN jtnfORARgsOYMghYRiqMC4iC6rfVlbM= ARC-Authentication-Results: i=1; imf19.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b=qKu73sMd; dmarc=pass (policy=reject) header.from=fb.com; spf=pass (imf19.hostedemail.com: domain of "prvs=12844fa265=alexlzhu@meta.com" designates 67.231.145.42 as permitted sender) smtp.mailfrom="prvs=12844fa265=alexlzhu@meta.com" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665615119; a=rsa-sha256; cv=none; b=XpPmXlfuBrmZw9+D8XHrczgSCquQlFaXvdbV1guwX1OZDokdwfgXIxjFsfX50eTTPEpRX+ lha2AEPvFOdQVoMDp7OyxhmgW1LzjXmgsL3owvA654SZgJMD5pBiJ04ErS3M0P/4tNcafu 1VdcZ/4uQ3oEBWK8mShKp2+AsByxO5o= X-Stat-Signature: 3sugj81dybndsphmca6e47xbk6nkhexh X-Rspamd-Queue-Id: 53C3B1A0027 Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b=qKu73sMd; dmarc=pass (policy=reject) header.from=fb.com; spf=pass (imf19.hostedemail.com: domain of "prvs=12844fa265=alexlzhu@meta.com" designates 67.231.145.42 as permitted sender) smtp.mailfrom="prvs=12844fa265=alexlzhu@meta.com" X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1665615119-341247 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: From: Alexander Zhu Transparent Hugepages use a larger page size of 2MB in comparison to normal sized pages that are 4kb. A larger page size allows for fewer TLB cache misses and thus more efficient use of the CPU. Using a larger page size also results in more memory waste, which can hurt performance in som= e use cases. THPs are currently enabled in the Linux Kernel by applications in limited virtual address ranges via the madvise system call. The THP shrinker tries to find a balance between increased use of THPs, and increased use of memory. It shrinks the size of memory by removing the underutilized THPs that are identified by the thp_utilization scanner.=20 In our experiments we have noticed that the least utilized THPs are almos= t entirely unutilized. Sample Output:=20 Utilized[0-50]: 1331 680884 Utilized[51-101]: 9 3983 Utilized[102-152]: 3 1187 Utilized[153-203]: 0 0 Utilized[204-255]: 2 539 Utilized[256-306]: 5 1135 Utilized[307-357]: 1 192 Utilized[358-408]: 0 0 Utilized[409-459]: 1 57 Utilized[460-512]: 400 13 Last Scan Time: 223.98s Last Scan Duration: 70.65s Above is a sample obtained from one of our test machines when THP is alwa= ys enabled. Of the 1331 THPs in this thp_utilization sample that have from 0-50 utilized subpages, we see that there are 680884 free pages. This comes out to 680884 / (512 * 1331) =3D 99.91% zero pages in the least utilized bucket. This represents 680884 * 4KB =3D 2.7GB memory waste. Also note that the vast majority of pages are either in the least utilize= d [0-50] or most utilized [460-512] buckets. The least utilized THPs are=20 responsible for almost all of the memory waste when THP is always=20 enabled. Thus by clearing out THPs in the lowest utilization bucket we extract most of the improvement in CPU efficiency. We have seen=20 similar results on our production hosts. This patchset introduces the THP shrinker we have developed to identify and split the least utilized THPs. It includes the thp_utilization=20 changes that groups anonymous THPs into buckets, the split_huge_page() changes that identify and zap zero 4KB pages within THPs and the shrinker changes. It should be noted that the split_huge_page() changes are based off previous work done by Yu Zhao.=20 In the future, we intend to allow additional tuning to the shrinker based on workload depending on CPU/IO/Memory pressure and the=20 amount of anonymous memory. The long term goal is to eventually always=20 enable THP for all applications and deprecate madvise entirely. In production we thus far have observed 2-3% reduction in overall cpu usage on stateless web servers when THP is always enabled. Alexander Zhu (3): mm: add thp_utilization metrics to debugfs mm: changes to split_huge_page() to free zero filled tail pages mm: THP low utilization shrinker Documentation/admin-guide/mm/transhuge.rst | 9 + include/linux/huge_mm.h | 10 + include/linux/list_lru.h | 24 ++ include/linux/mm_types.h | 5 + include/linux/rmap.h | 2 +- include/linux/vm_event_item.h | 3 + mm/huge_memory.c | 360 +++++++++++++++++- mm/list_lru.c | 49 +++ mm/migrate.c | 72 +++- mm/migrate_device.c | 4 +- mm/page_alloc.c | 6 + mm/vmstat.c | 3 + .../selftests/vm/split_huge_page_test.c | 113 +++++- tools/testing/selftests/vm/vm_util.c | 23 ++ tools/testing/selftests/vm/vm_util.h | 3 + 15 files changed, 669 insertions(+), 17 deletions(-) --=20 2.30.2