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 2A5D7C4167D for ; Tue, 31 Oct 2023 17:45:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346927AbjJaRpK (ORCPT ); Tue, 31 Oct 2023 13:45:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54732 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346977AbjJaRpG (ORCPT ); Tue, 31 Oct 2023 13:45:06 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5D5C0C2 for ; Tue, 31 Oct 2023 10:45:02 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-da13698a6d3so5052268276.0 for ; Tue, 31 Oct 2023 10:45:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698774301; x=1699379101; darn=vger.kernel.org; h=to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=4RErP287JmMTq7RMYkFt2o0RxUiLJfWTr4XJXoK087k=; b=ZxZOrvRwuu1vp8hmlRAA+RT0Je5ulHjNWoOfB4E9ly8sOzcXeGFqhNQ9gLz8JsNnRB mn6pzWTAPboJNt+WNzbUklCeF80fBVici9myIUMDey7zzzPlJyakbDpLD1hLf1Mlt6lU Y//Fwn/tohhy+Lo17J/zqw9kIwcBMmUCciqFnIUpjbMfenuvrG/2wmogFvK1e+I1N1XM 7lG6onvmgYJf/eHIF7JlB6wUQdpdq7dkrpbNLq4OBXBzFfOzEYh4mlH6wq3QYJfkMz8k 24FoPh6fCkvc/dFb+kA2jvwcNWc41CssYfhWqRSsxFyyn9DJXPah6lnswGSucM7T6lta rbhg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698774301; x=1699379101; h=to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=4RErP287JmMTq7RMYkFt2o0RxUiLJfWTr4XJXoK087k=; b=XQmiJ5z6ywQvkeGn7Jr4gz1OYPvpVWhIko0ooNvpHVM0qh27AzfA4PZVF1GeHCGPl3 3oJ+aIk5bByrRk5Q7Q41pglHUD3UPWPP6z87Ek8fFwQww/yj/S/Ru96TRlawULrSBaO+ QTow13uXEHcKK4qR/GXWM1/iRfEmod1LSlJph8GkC0mkvxwVJdLdu97iQgDV84nqHDEb ZmCNEkrVr0OlUbYAn7FzGASVo3vF+6clO42GJ/dkfzKqiKxwI0Q4DrP6LYQxw3amffPb dri3J/qODD413AzPjCICR+7pQDG9XyRmpR8cKSPCVKSuXV94r09vdbduoYLYSRtjgVYa svNw== X-Gm-Message-State: AOJu0Yw8UPiY7AKerA0qXVBFFALV6lKxSvg+bdCROquiC3I5cLpN1B3l 03qws0I3Ju3EjdFQNFEQWvJ604W3yW7oMEJmgw== X-Google-Smtp-Source: AGHT+IGF+swsalLbjyalKCjGHosPkOKAM33GIZb7qWKiSJci1IwXcbpCIrifO0+POvPgYWVOttq1dyvPgUe86sUw8A== X-Received: from souravpanda.svl.corp.google.com ([2620:15c:2a3:200:84c2:bfa0:7c62:5d77]) (user=souravpanda job=sendgmr) by 2002:a25:ac04:0:b0:d9a:520f:1988 with SMTP id w4-20020a25ac04000000b00d9a520f1988mr257775ybi.4.1698774301382; Tue, 31 Oct 2023 10:45:01 -0700 (PDT) Date: Tue, 31 Oct 2023 10:44:58 -0700 Mime-Version: 1.0 X-Mailer: git-send-email 2.42.0.820.g83a721a137-goog Message-ID: <20231031174459.459480-1-souravpanda@google.com> Subject: [PATCH v3 0/1] mm: report per-page metadata information From: Sourav Panda To: corbet@lwn.net, gregkh@linuxfoundation.org, rafael@kernel.org, akpm@linux-foundation.org, mike.kravetz@oracle.com, muchun.song@linux.dev, rppt@kernel.org, david@redhat.com, rdunlap@infradead.org, chenlinxuan@uniontech.com, yang.yang29@zte.com.cn, souravpanda@google.com, tomas.mudrunka@gmail.com, bhelgaas@google.com, ivan@cloudflare.com, pasha.tatashin@soleen.com, yosryahmed@google.com, hannes@cmpxchg.org, shakeelb@google.com, kirill.shutemov@linux.intel.com, wangkefeng.wang@huawei.com, adobriyan@gmail.com, vbabka@suse.cz, Liam.Howlett@Oracle.com, surenb@google.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, willy@infradead.org, weixugc@google.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Changelog: v3: - Addressed comment from Matthew Wilcox. - In free_page_ext, page_pgdat() is now extracted prior to freeing the memory. v2: - Fixed the three bugs reported by kernel test robot. - Enhanced the commit message as recommended by David Hildenbrand. - Addressed comments from Matthew Wilcox: - Simplified alloc_vmemmap_page_list() and free_page_ext() as recommended. - Used the appropriate comment style in mm/vmstat.c. - Replaced writeout_early_perpage_metadata() with store_early_perpage_metadata() to reduce ambiguity with what swap does. - Addressed comments from Mike Rapoport: - Simplified the loop in alloc_vmemmap_page_list(). - Could NOT address a comment to move store_early_perpage_metadata() near where nodes and page allocator are initialized. - Included the vmalloc()ed page_ext in accounting within free_page_ext(). - Made early_perpage_metadata[MAX_NUMNODES] static. Previous approaches and discussions ----------------------------------- v2: https://lore.kernel.org/all/20231018005548.3505662-1-souravpanda@google.com v1: https://lore.kernel.org/r/20230913173000.4016218-2-souravpanda@google.com Hi! This patch adds a new per-node PageMetadata field to /sys/devices/system/node/nodeN/meminfo and a global PageMetadata field to /proc/meminfo. This information can be used by users to see how much memory is being used by per-page metadata, which can vary depending on build configuration, machine architecture, and system use. Per-page metadata is the amount of memory that Linux needs in order to manage memory at the page granularity. The majority of such memory is used by "struct page" and "page_ext" data structures. Background ---------- Kernel overhead observability is missing some of the largest allocations during runtime, including vmemmap (struct pages) and page_ext. This patch aims to address this problem by exporting a new metric PageMetadata. On the contrary, the kernel does provide observibility for boot memory allocations. For example, the metric reserved_pages depicts the pages allocated by the bootmem allocator. This can be simply calculated as present_pages - managed_pages, which are both exported in /proc/zoneinfo. The metric reserved_pages is primarily composed of struct pages and page_ext. What about the struct pages (allocated by bootmem allocator) that are free'd during hugetlbfs allocations and then allocated by buddy-allocator once hugtlbfs pages are free'd? /proc/meminfo MemTotal changes: MemTotal does not include memblock allocations but includes buddy allocations. However, during runtime memblock allocations can be shifted into buddy allocations, and therefore become part of MemTotal. Once the struct pages get allocated by buddy allocator, we lose track of these struct page allocations overhead accounting. Therefore, we must export a new metric that we shall refer to as PageMetadata (exported by node). This shall also comprise the struct page and page_ext allocations made during runtime. Results and analysis -------------------- Memory model: Sparsemem-vmemmap $ echo 1 > /proc/sys/vm/hugetlb_optimize_vmemmap $ cat /proc/meminfo | grep MemTotal MemTotal: 32918196 kB $ cat /proc/meminfo | grep Meta PageMetadata: 589824 kB $ cat /sys/devices/system/node/node0/meminfo | grep Meta Node 0 PageMetadata: 294912 kB $ cat /sys/devices/system/node/node1/meminfo | grep Meta Node 1 PageMetadata: 294912 kB AFTER HUGTLBFS RESERVATION $ echo 512 > /proc/sys/vm/nr_hugepages $ cat /proc/meminfo | grep MemTotal MemTotal: 32934580 kB $ cat /proc/meminfo | grep Meta PageMetadata: 575488 kB $ cat /sys/devices/system/node/node0/meminfo | grep Meta Node 0 PageMetadata: 287744 kB $ cat /sys/devices/system/node/node1/meminfo | grep Meta Node 1 PageMetadata: 287744 kB AFTER FREEING HUGTLBFS RESERVATION $ echo 0 > /proc/sys/vm/nr_hugepages $ cat /proc/meminfo | grep MemTotal MemTotal: 32934580 kB $ cat /proc/meminfo | grep Meta PageMetadata: 589824 kB $ cat /sys/devices/system/node/node0/meminfo | grep Meta Node 0 PageMetadata: 294912 kB $ cat /sys/devices/system/node/node1/meminfo | grep Meta Node 1 PageMetadata: 294912 kB Sourav Panda (1): mm: report per-page metadata information Documentation/filesystems/proc.rst | 3 +++ drivers/base/node.c | 2 ++ fs/proc/meminfo.c | 7 +++++++ include/linux/mmzone.h | 3 +++ include/linux/vmstat.h | 4 ++++ mm/hugetlb.c | 8 +++++++- mm/hugetlb_vmemmap.c | 8 +++++++- mm/mm_init.c | 3 +++ mm/page_alloc.c | 1 + mm/page_ext.c | 32 +++++++++++++++++++++--------- mm/sparse-vmemmap.c | 3 +++ mm/sparse.c | 7 ++++++- mm/vmstat.c | 24 ++++++++++++++++++++++ 13 files changed, 93 insertions(+), 12 deletions(-) -- 2.42.0.820.g83a721a137-goog