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 X-Spam-Level: X-Spam-Status: No, score=-6.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_GIT autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6C0CC43461 for ; Tue, 15 Sep 2020 13:00:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id F1E8320756 for ; Tue, 15 Sep 2020 13:00:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=bytedance-com.20150623.gappssmtp.com header.i=@bytedance-com.20150623.gappssmtp.com header.b="B9ojoIjD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F1E8320756 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5043290002A; Tue, 15 Sep 2020 09:00:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4B23B6B00A6; Tue, 15 Sep 2020 09:00:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 379C290002A; Tue, 15 Sep 2020 09:00:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0033.hostedemail.com [216.40.44.33]) by kanga.kvack.org (Postfix) with ESMTP id 1B73B6B00A4 for ; Tue, 15 Sep 2020 09:00:18 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id CC5238249980 for ; Tue, 15 Sep 2020 13:00:17 +0000 (UTC) X-FDA: 77265304074.14.sack00_3c10fa127111 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id 7A74718012B2A for ; Tue, 15 Sep 2020 13:00:10 +0000 (UTC) X-HE-Tag: sack00_3c10fa127111 X-Filterd-Recvd-Size: 9735 Received: from mail-pl1-f195.google.com (mail-pl1-f195.google.com [209.85.214.195]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Tue, 15 Sep 2020 13:00:09 +0000 (UTC) Received: by mail-pl1-f195.google.com with SMTP id j7so1299223plk.11 for ; Tue, 15 Sep 2020 06:00:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=IFig9ACO4bSS32kx/lDqlgTRWm2lqua6M6hUcvyGFR8=; b=B9ojoIjDFZ9eF0ICOMpjQvnzYZWgEFslXcMRchF5bHGTN+Gs/cQhddDbUEdXc6MeyB R+TMnXJoPPxmQwJ56a9Gnc01PpUNBX1HIANP0gYofuAA3aAmgq+tvGo8U6HiqIm0C/J0 oEIAe6LSlOXWtpadXOgFatYpd6+V6hATPrGv2gLfOM/1cwTEe0n4atiy3M40UeuoTaXn y/NstleAjNRdvriNCxTKAdt3OvF/KC2gGdvH5sjewgWAeb3PKRA02U+bdiLympzTrsPV YoNhH97t7Dd7k9wcRYVVMVdkTmZ0WJZGpElS0kZUAzHxwu+yOIekQSpcGXzhznPTCLNt Byrg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=IFig9ACO4bSS32kx/lDqlgTRWm2lqua6M6hUcvyGFR8=; b=AfZbWnyucYnWh8p0zObuER1Q8DFwgab+Tg0qyrwpBMRRtmL5PyoIUNhMvL5wamGZ5c AIzI6ic9nd5tslDINDWQcIvcqabBmQkSNn9sP9GE+3uKV+dTNhEFMD7JHl03hjazaYRo aeorFxWf4hHpXSlFmBrnlsNjmREKbmZpR32CGeqFSW+KVH0MEDdw+r79WJuif6+ELYs0 /LAaxojD6ReIf1OEME7U24/yUt1bcQKGOacxWtfC2m2RBUqPRY/xF0I/9PYnsUYz+0rN 5QF6HVndfxvwo1Fn3K0fPzFnLcQjtAHd6h2YbQbS3jDBZmG9i+VyItwRnAo7LoeQund9 tkKA== X-Gm-Message-State: AOAM5338ZsmShcaBVAh5n2S3i0S6kHW/pOCcrLOaHOVjx1C79/RRM18v VC3+qnqCCQaArek9tOE/basj+w== X-Google-Smtp-Source: ABdhPJweCFGKb+8Bpk7lpOwwgL1O+W4g/G43QI96b0WrwCjZbzTFpN+tMKrXVGoqnvzds1F5KoKRqA== X-Received: by 2002:a17:90b:2347:: with SMTP id ms7mr3974046pjb.135.1600174807782; Tue, 15 Sep 2020 06:00:07 -0700 (PDT) Received: from localhost.bytedance.net ([103.136.220.66]) by smtp.gmail.com with ESMTPSA id w185sm14269855pfc.36.2020.09.15.05.59.58 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 15 Sep 2020 06:00:07 -0700 (PDT) From: Muchun Song To: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Muchun Song Subject: [RFC PATCH 00/24] mm/hugetlb: Free some vmemmap pages of hugetlb page Date: Tue, 15 Sep 2020 20:59:23 +0800 Message-Id: <20200915125947.26204-1-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) MIME-Version: 1.0 X-Rspamd-Queue-Id: 7A74718012B2A X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 Content-Transfer-Encoding: quoted-printable 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: Hi all, This patch series will free some vmemmap pages(struct page structures) associated with each hugetlbpage when preallocated to save memory. Nowadays we track the status of physical page frames using `struct page` arranged in one or more arrays. And here exists one-to-one mapping betwee= n the physical page frame and the corresponding `struct page`. The hugetlbpage support is built on top of multiple page size support that is provided by most modern architectures. For example, x86 CPUs normally support 4K and 2M (1G if architecturally supported) page sizes. Every hugetlbpage has more than one `struct page`. The 2M hugetlbpage has 512 `struct page` and 1G hugetlbpage has 4096 `struct page`. But in the core of hugetlbpage only uses the first 4 `struct page` to store metadata associated with each hugetlbpage. The rest of the `struct page` are usually read the compound_head field which are all the same value. If we can free some struct page memory to buddy system so that We can save a lot of memory. When the system boot up, every 2M hugetlbpage has 512 `struct page` which is 8 pages(sizeof(struct page) * 512 / PAGE_SIZE). hugetlbpage struct page(8 pages) page frame= (8 pages) +-----------+ ---virt_to_page---> +-----------+ mapping to +-------= ----+ | | | 0 | -------------> | 0 = | | | | 1 | -------------> | 1 = | | | | 2 | -------------> | 2 = | | | | 3 | -------------> | 3 = | | | | 4 | -------------> | 4 = | | 2M | | 5 | -------------> | 5 = | | | | 6 | -------------> | 6 = | | | | 7 | -------------> | 7 = | | | +-----------+ +-------= ----+ | | | | +-----------+ When a hugetlbpage is preallocated, we can change the mapping from above = to bellow. hugetlbpage struct page(8 pages) page frame= (8 pages) +-----------+ ---virt_to_page---> +-----------+ mapping to +-------= ----+ | | | 0 | -------------> | 0 = | | | | 1 | -------------> | 1 = | | | | 2 | -------------> +-------= ----+ | | | 3 | -----------------^ ^ ^ = ^ ^ | | | 4 | -------------------+ | = | | | 2M | | 5 | ---------------------+ = | | | | | 6 | -----------------------= + | | | | 7 | -----------------------= --+ | | +-----------+ | | | | +-----------+ The mapping of the first page(index 0) and the second page(index 1) is unchanged. The remaining 6 pages are all mapped to the same page(index 1). So we only need 2 pages for vmemmap area and free 6 pages to the buddy system to save memory. Why we can do this? Because the content of the remaining 7 pages are usually same except the first page. When a hugetlbpage is freed to the buddy system, we should allocate 6 pages for vmemmap pages and restore the previous mapping relationship. If we uses the 1G hugetlbpage, we can save 4095 pages. This is a very substantial gain. On our server, run some SPDK applications which will use 300GB hugetlbpage. With this feature enabled, we can save 4797MB memory. Muchun Song (24): mm/memory_hotplug: Move bootmem info registration API to bootmem_info.c mm/memory_hotplug: Move {get,put}_page_bootmem() to bootmem_info.c mm/hugetlb: Introduce a new config HUGETLB_PAGE_FREE_VMEMMAP mm/hugetlb: Register bootmem info when CONFIG_HUGETLB_PAGE_FREE_VMEMMAP mm/hugetlb: Introduce nr_free_vmemmap_pages in the struct hstate mm/hugetlb: Introduce pgtable allocation/freeing helpers mm/hugetlb: Add freeing unused vmemmap pages support for x86 mm/bootmem_info: Introduce {free,prepare}_vmemmap_page() x86/mm: Introduce VMEMMAP_SIZE/VMEMMAP_END macro mm/hugetlb: Free the vmemmap pages associated with each hugetlb page mm/hugetlb: Add vmemmap_pmd_huge macro for x86 mm/hugetlb: Defer freeing of hugetlb pages mm/hugetlb: Allocate the vmemmap pages associated with each hugetlb page mm/hugetlb: Introduce remap_huge_page_pmd_vmemmap helper mm/hugetlb: Use PG_slab to indicate split pmd mm/hugetlb: Support freeing vmemmap pages of gigantic page mm/hugetlb: Add a BUILD_BUG_ON to check if struct page size is a power of two mm/hugetlb: Clear PageHWPoison on the non-error memory page mm/hugetlb: Flush work when dissolving hugetlb page mm/hugetlb: Add a kernel parameter hugetlb_free_vmemmap mm/hugetlb: Merge pte to huge pmd only for gigantic page mm/hugetlb: Implement vmemmap_pmd_mkhuge macro mm/hugetlb: Gather discrete indexes of tail page mm/hugetlb: Add BUILD_BUG_ON to catch invalid usage of tail struct page .../admin-guide/kernel-parameters.txt | 9 + Documentation/admin-guide/mm/hugetlbpage.rst | 3 + arch/x86/include/asm/hugetlb.h | 20 + arch/x86/include/asm/pgtable_64_types.h | 8 + arch/x86/mm/init_64.c | 5 +- fs/Kconfig | 15 + include/linux/bootmem_info.h | 65 ++ include/linux/hugetlb.h | 64 ++ include/linux/hugetlb_cgroup.h | 15 +- include/linux/memory_hotplug.h | 27 - mm/Makefile | 1 + mm/bootmem_info.c | 125 +++ mm/hugetlb.c | 834 +++++++++++++++++- mm/memory_hotplug.c | 116 --- mm/sparse.c | 1 + 15 files changed, 1143 insertions(+), 165 deletions(-) create mode 100644 include/linux/bootmem_info.h create mode 100644 mm/bootmem_info.c --=20 2.20.1