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 0A207C32771 for ; Wed, 28 Sep 2022 06:25:27 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 24A008E0123; Wed, 28 Sep 2022 02:25:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1F9838E0120; Wed, 28 Sep 2022 02:25:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 09B3A8E0123; Wed, 28 Sep 2022 02:25:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id EB4E18E0120 for ; Wed, 28 Sep 2022 02:25:26 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id A4FD31C6AA0 for ; Wed, 28 Sep 2022 06:25:26 +0000 (UTC) X-FDA: 79960507452.30.BCFE696 Received: from mx0a-00082601.pphosted.com (mx0b-00082601.pphosted.com [67.231.153.30]) by imf13.hostedemail.com (Postfix) with ESMTP id E9E2020017 for ; Wed, 28 Sep 2022 06:25:18 +0000 (UTC) Received: from pps.filterd (m0089730.ppops.net [127.0.0.1]) by m0089730.ppops.net (8.17.1.5/8.17.1.5) with ESMTP id 28S2M1Y8027654 for ; Tue, 27 Sep 2022 23:25:16 -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=jpmExJOMfUyiPBPrMzdNoEt1u3hhVBVx1hncwAZBOZs=; b=Dl/de+x2j/YZig54/H91vY+92dE5YKanxI4j/V4h6g2NCuC1EzcA+LJz7DeT02Ce1ZVG HVVF72BRCv6Tnd94jk4jCPDgs3g46DEyHvQW8sqBvvJ5QkJJmkSS7gegpR3JfbIwz6kQ omJCLFc0RCPOVGSYoalbBvCfYLvwH1R25xI= Received: from maileast.thefacebook.com ([163.114.130.16]) by m0089730.ppops.net (PPS) with ESMTPS id 3juw2xqy8f-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 27 Sep 2022 23:25:16 -0700 Received: from twshared12430.23.frc3.facebook.com (2620:10d:c0a8:1b::d) by mail.thefacebook.com (2620:10d:c0a8:82::d) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 27 Sep 2022 23:25:15 -0700 Received: by devvm6390.atn0.facebook.com (Postfix, from userid 352741) id 6B8B0443E381; Tue, 27 Sep 2022 23:25:09 -0700 (PDT) From: To: CC: , , , , , , Alexander Zhu Subject: [PATCH 0/3] THP Shrinker Date: Tue, 27 Sep 2022 23:25:03 -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: lX6tB4F7yjY6iAsWADc1mQ1Y30TaVsLQ X-Proofpoint-ORIG-GUID: lX6tB4F7yjY6iAsWADc1mQ1Y30TaVsLQ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.528,FMLib:17.11.122.1 definitions=2022-09-28_02,2022-09-27_01,2022-06-22_01 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1664346326; 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=jpmExJOMfUyiPBPrMzdNoEt1u3hhVBVx1hncwAZBOZs=; b=8XQdKvsImUmaJD10SI7bwefq6W+ySh6fRYpe26VV8o1VgK10g/UXGYgywxg7Ev1QbTYQKb LyshCFMIbXEz/QE4Fst0hbMaCEicNIvOpdJ/7DJLd7PvCyV9uJiZf6AWfYCOjtIxrZeHxH NUB6lZmZZPwCLv1ZNshTYi0E7WMtPMU= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b="Dl/de+x2"; dmarc=pass (policy=reject) header.from=fb.com; spf=pass (imf13.hostedemail.com: domain of "prvs=0270d06900=alexlzhu@fb.com" designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=0270d06900=alexlzhu@fb.com" ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1664346326; a=rsa-sha256; cv=none; b=0PQcVqzlmfWE279PfYR76v15jMDY+iI+61Ul+qOAdqjYeM1hNEW+tgHwoIIqJviABznORI jXdgpZbyNN0nnIg3aE7oe5+Tor0mZrxQLvvaFmYdW9AJrtH8WTe9jlhyZ1Ty2kVfI1pAEG BJaZhFPWKJBOSv8Ygdv//eMsL5Kthd0= Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=fb.com header.s=facebook header.b="Dl/de+x2"; dmarc=pass (policy=reject) header.from=fb.com; spf=pass (imf13.hostedemail.com: domain of "prvs=0270d06900=alexlzhu@fb.com" designates 67.231.153.30 as permitted sender) smtp.mailfrom="prvs=0270d06900=alexlzhu@fb.com" X-Rspamd-Server: rspam02 X-Stat-Signature: zs4tye69u7tu6oasumtraqsqx6yc68q3 X-Rspamd-Queue-Id: E9E2020017 X-Rspam-User: X-HE-Tag: 1664346318-979196 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 | 306 +++++++++++++++++- 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 | 114 ++++++- tools/testing/selftests/vm/vm_util.c | 23 ++ tools/testing/selftests/vm/vm_util.h | 1 + 15 files changed, 613 insertions(+), 18 deletions(-) --=20 2.30.2