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 29C45C3DA6E for ; Wed, 10 Jan 2024 11:00:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B720F6B0098; Wed, 10 Jan 2024 06:00:38 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B22D96B0099; Wed, 10 Jan 2024 06:00:38 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 99C236B009A; Wed, 10 Jan 2024 06:00:38 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) by kanga.kvack.org (Postfix) with ESMTP id 8A64E6B0098 for ; Wed, 10 Jan 2024 06:00:38 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 51A9EC0A6A for ; Wed, 10 Jan 2024 11:00:38 +0000 (UTC) X-FDA: 81663108156.14.B42FBAE Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf02.hostedemail.com (Postfix) with ESMTP id CB19480018 for ; Wed, 10 Jan 2024 11:00:34 +0000 (UTC) Authentication-Results: imf02.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=HoWLmhB1; spf=pass (imf02.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1704884434; 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:in-reply-to:references:references:dkim-signature; bh=Iq5kMPG032L2XMRVBN8DQs9rzCJIeaz/FqIMJu5B/6A=; b=z/WH1QNBzmoTEPU4FvuGlzn9tj2rJaixtpXcgQW7vaC6Ekeanwc5XfhuBAuNQQLU37kZq2 titlgCORAqNBH4dXX6LP4TyoImRZUAnPG6Gi10mBXHX8i1xuf/+xbRm2YpTL358jLZh92d ZkewxkDhIdUnOBxTfSvfKzajAyD35pk= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1704884435; a=rsa-sha256; cv=none; b=hARqQO0TDz77ml1U62XbB0XolpYfzKXlNHSoSpxg1uEvsnS9lnqZBSAMQtpHx8rWaX6I+0 tqINPdr82PyAIxPpCJJIEz6EYx/Noyd5d6XoeknuBrBqRnmFHFSDeD9sP6exAstQPhc0Un qvaZS80/4NDf6AlaHmYZkCzUv1dSL8o= ARC-Authentication-Results: i=1; imf02.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=HoWLmhB1; spf=pass (imf02.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1704884434; h=from:from: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:in-reply-to:references:references:autocrypt:autocrypt; bh=Iq5kMPG032L2XMRVBN8DQs9rzCJIeaz/FqIMJu5B/6A=; b=HoWLmhB1VviYEWudAuCnjk+eFPNKMs2aJggSeuV355LRO9FXxleZWI4y9YjFFw3YTs95il W+sD8MZrWcLPGUc3lj/ozXdxPQ691k44HDqyJfipZs6kIvR98t9qNmfF+rXkZFOJvmwV3F Nb/elSBwE02H0miFAEay+jX5MBfuP0E= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-660-1T3fk7hJPUGtp6lOA7K4Sw-1; Wed, 10 Jan 2024 06:00:32 -0500 X-MC-Unique: 1T3fk7hJPUGtp6lOA7K4Sw-1 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-40e4c1dd8a3so15487435e9.0 for ; Wed, 10 Jan 2024 03:00:32 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1704884431; x=1705489231; h=content-transfer-encoding:in-reply-to:organization:autocrypt:from :references:cc:to:content-language:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Iq5kMPG032L2XMRVBN8DQs9rzCJIeaz/FqIMJu5B/6A=; b=og9dKE8Be/KF3CBitF9dWIkUKvfqTrGY/9+sWo4s49UMglTW6LrG4MB9vtOhqqus6H BY1pmgEA32SBJDoKybsw8pL152f6iQkw5fyAof1r0WZxog5YUWXGQRHyXGeUnZ6bX5QY 0KI9zPdtDioLXnFmAFg5RVQGGFdViNBAFTvoMp5YtbtjDVIh3ZeSMqMu/aBQ/JI7joWf 0uk178hjRqZyNT7aSZriiKLoLO2waFWQ9IuExIWAXcl46ziuozVHgV2XHHQ3PzpAVs99 dIgevzF7bdnuFqWzVijEPSEyxgN5JHCu7mdwwO9/TSX2mfVk3x0I7zhuWRKuq7l7xovx aV4Q== X-Gm-Message-State: AOJu0YzbWkmaRENzAYbbHcPNyuySa1DcFXBJ9ob1jpkoRD6XDHMEPfae uUpyu1Jom7p6wxpM79WgDNt4SiCPQ2z1C+L7ouwZicctylVIllgU9+iwm6+tek5wfDcN56SfBlf 5ualZsnv3nnvLsyVvM9U= X-Received: by 2002:a05:600c:5111:b0:40e:556d:7885 with SMTP id o17-20020a05600c511100b0040e556d7885mr471457wms.165.1704884431337; Wed, 10 Jan 2024 03:00:31 -0800 (PST) X-Google-Smtp-Source: AGHT+IEP6L4OXvZsVhZnmY6ESX1ytsi65eQT0O0Vol4zHgQX0mLcMnOgeiTMjwBPJsBrPRRP1tmtSg== X-Received: by 2002:a05:600c:5111:b0:40e:556d:7885 with SMTP id o17-20020a05600c511100b0040e556d7885mr471438wms.165.1704884430773; Wed, 10 Jan 2024 03:00:30 -0800 (PST) Received: from ?IPV6:2003:cb:c73d:de00:7cf7:9482:e5dc:6ad0? (p200300cbc73dde007cf79482e5dc6ad0.dip0.t-ipconnect.de. [2003:cb:c73d:de00:7cf7:9482:e5dc:6ad0]) by smtp.gmail.com with ESMTPSA id j28-20020a05600c1c1c00b0040e52f0e207sm468947wms.0.2024.01.10.03.00.29 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 10 Jan 2024 03:00:30 -0800 (PST) Message-ID: Date: Wed, 10 Jan 2024 12:00:29 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v1] tools/mm: Add thpmaps script to dump THP usage info To: Ryan Roberts , Barry Song <21cnbao@gmail.com> Cc: John Hubbard , Andrew Morton , Zenghui Yu , Matthew Wilcox , Kefeng Wang , Zi Yan , Alistair Popple , linux-mm@kvack.org References: <20240102153828.1002295-1-ryan.roberts@arm.com> <4e7445a0-acc9-487f-999f-a2b6d03d265e@nvidia.com> <3bd5e4a3-9f67-4483-9a0e-9abb5eb783cd@arm.com> <94ebe62b-5f55-4be9-b464-4105b4692496@arm.com> <68d5ce7e-6587-47c6-bd0f-988adf5d92a4@arm.com> <974a2670-7fa9-425e-921e-8d54a596e6cf@arm.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <974a2670-7fa9-425e-921e-8d54a596e6cf@arm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Stat-Signature: ncb9eno3cnrzjwwo7e98rqyojhq9f4ze X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: CB19480018 X-Rspam-User: X-HE-Tag: 1704884434-612487 X-HE-Meta: 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 Lm3kSaMv 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 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: List-Subscribe: List-Unsubscribe: On 10.01.24 11:55, Ryan Roberts wrote: > On 10/01/2024 10:42, David Hildenbrand wrote: >> On 10.01.24 11:38, Ryan Roberts wrote: >>> On 10/01/2024 10:30, Barry Song wrote: >>>> On Wed, Jan 10, 2024 at 6:23 PM Ryan Roberts wrote: >>>>> >>>>> On 10/01/2024 09:09, Barry Song wrote: >>>>>> On Wed, Jan 10, 2024 at 4:58 PM Ryan Roberts wrote: >>>>>>> >>>>>>> On 10/01/2024 08:02, Barry Song wrote: >>>>>>>> On Wed, Jan 10, 2024 at 12:16 PM John Hubbard wrote: >>>>>>>>> >>>>>>>>> On 1/9/24 19:51, Barry Song wrote: >>>>>>>>>> On Wed, Jan 10, 2024 at 11:35 AM John Hubbard wrote: >>>>>>>>> ... >>>>>>>>>>> Hi Ryan, >>>>>>>>>>> >>>>>>>>>>> One thing that immediately came up during some recent testing of mTHP >>>>>>>>>>> on arm64: the pid requirement is sometimes a little awkward. I'm running >>>>>>>>>>> tests on a machine at a time for now, inside various containers and >>>>>>>>>>> such, and it would be nice if there were an easy way to get some numbers >>>>>>>>>>> for the mTHPs across the whole machine. >>>>>>> >>>>>>> Just to confirm, you're expecting these "global" stats be truely global >>>>>>> and not >>>>>>> per-container? (asking because you exploicitly mentioned being in a >>>>>>> container). >>>>>>> If you want per-container, then you can probably just create the container >>>>>>> in a >>>>>>> cgroup? >>>>>>> >>>>>>>>>>> >>>>>>>>>>> I'm not sure if that changes anything about thpmaps here. Probably >>>>>>>>>>> this is fine as-is. But I wanted to give some initial reactions from >>>>>>>>>>> just some quick runs: the global state would be convenient. >>>>>>> >>>>>>> Thanks for taking this for a spin! Appreciate the feedback. >>>>>>> >>>>>>>>>> >>>>>>>>>> +1. but this seems to be impossible by scanning pagemap? >>>>>>>>>> so may we add this statistics information in kernel just like >>>>>>>>>> /proc/meminfo or a separate /proc/mthp_info? >>>>>>>>>> >>>>>>>>> >>>>>>>>> Yes. From my perspective, it looks like the global stats are more useful >>>>>>>>> initially, and the more detailed per-pid or per-cgroup stats are the >>>>>>>>> next level of investigation. So feels odd to start with the more >>>>>>>>> detailed stats. >>>>>>>>> >>>>>>>> >>>>>>>> probably because this can be done without the modification of the kernel. >>>>>>> >>>>>>> Yes indeed, as John said in an earlier thread, my previous attempts to add >>>>>>> stats >>>>>>> directly in the kernel got pushback; DavidH was concerned that we don't >>>>>>> really >>>>>>> know exectly how to account mTHPs yet >>>>>>> (whole/partial/aligned/unaligned/per-size/etc) so didn't want to end up >>>>>>> adding >>>>>>> the wrong ABI and having to maintain it forever. There has also been some >>>>>>> pushback regarding adding more values to multi-value files in sysfs, so David >>>>>>> was suggesting coming up with a whole new scheme at some point (I know >>>>>>> /proc/meminfo isn't sysfs, but the equivalent files for NUMA nodes and >>>>>>> cgroups >>>>>>> do live in sysfs). >>>>>>> >>>>>>> Anyway, this script was my attempt to 1) provide a short term solution to the >>>>>>> "we need some stats" request and 2) provide a context in which to explore >>>>>>> what >>>>>>> the right stats are - this script can evolve without the ABI problem. >>>>>>> >>>>>>>> The detailed per-pid or per-cgroup is still quite useful to my case in which >>>>>>>> we set mTHP enabled/disabled and allowed sizes according to vma types, >>>>>>>> eg. libc_malloc, java heaps etc. >>>>>>>> >>>>>>>> Different vma types can have different anon_name. So I can use the detailed >>>>>>>> info to find out if specific VMAs have gotten mTHP properly and how many >>>>>>>> they have gotten. >>>>>>>> >>>>>>>>> However, Ryan did clearly say, above, "In future we may wish to >>>>>>>>> introduce stats directly into the kernel (e.g. smaps or similar)". And >>>>>>>>> earlier he ran into some pushback on trying to set up /proc or /sys >>>>>>>>> values because this is still such an early feature. >>>>>>>>> >>>>>>>>> I wonder if we could put the global stats in debugfs for now? That's >>>>>>>>> specifically supposed to be a "we promise *not* to keep this ABI stable" >>>>>>>>> location. >>>>>>> >>>>>>> Now that I think about it, I wonder if we can add a --global mode to the >>>>>>> script >>>>>>> (or just infer global when neither --pid nor --cgroup are provided). I >>>>>>> think I >>>>>>> should be able to determine all the physical memory ranges from /proc/iomem, >>>>>>> then grab all the info we need from /proc/kpageflags. We should then be >>>>>>> able to >>>>>>> process it all in much the same way as for --pid/--cgroup and provide the >>>>>>> same >>>>>>> stats, but it will apply globally. What do you think? >>>>> >>>>> Having now thought about this for a few mins (in the shower, if anyone wants >>>>> the >>>>> complete picture :) ), this won't quite work. This approach doesn't have the >>>>> virtual mapping information so the best it can do is tell us "how many of each >>>>> size of THP are allocated?" - it doesn't tell us anything about whether they >>>>> are >>>>> fully or partially mapped or what their alignment is (all necessary if we want >>>>> to know if they are contpte-mapped). So I don't think this approach is going to >>>>> be particularly useful. >>>>> >>>>> And this is also the big problem if we want to gather stats inside the kernel; >>>>> if we want something equivalant to /proc/meminfo's >>>>> AnonHugePages/ShmemPmdMapped/FilePmdMapped, we need to consider not just the >>>>> allocation of the THP but also whether it is mapped. That's easy for >>>>> PMD-mappings, because there is only one entry to consider - when you set it, >>>>> you >>>>> increment the number of PMD-mapped THPs, when you clear it, you decrement. But >>>>> for PTE-mappings it's harder; you know the size when you are mapping so its >>>>> easy >>>>> to increment, but you can do a partial unmap, so you would need to scan the >>>>> PTEs >>>>> to figure out if we are unmapping the first page of a previously >>>>> fully-PTE-mapped THP, which is expensive. We would need a cheap mechanism to >>>>> determine "is this folio fully and contiguously mapped in at least one >>>>> process?". >>>> >>>> as OPPO's approach I shared to you before is maintaining two mapcount >>>> 1. entire map >>>> 2. subpage's map >>>> 3. if 1 and 2 both exist, it is DoubleMapped. >>>> >>>> This isn't a problem for us. and everytime if we do a partial unmap, >>>> we have an explicit >>>> cont_pte split which will decrease the entire map and increase the >>>> subpage's mapcount. >>>> >>>> but its downside is that we expose this info to mm-core. >>> >>> OK, but I think we have a slightly more generic situation going on with the >>> upstream; If I've understood correctly, you are using the PTE_CONT bit in the >>> PTE to determne if its fully mapped? That works for your case where you only >>> have 1 size of THP that you care about (contpte-size). But for the upstream, we >>> have multi-size THP so we can't use the PTE_CONT bit to determine if its fully >>> mapped because we can only use that bit if the THP is at least 64K and aligned, >>> and only on arm64. We would need a SW bit for this purpose, and the mm would >>> need to update that SW bit for every PTE one the full -> partial map transition. >> >> Oh no. Let's not make everything more complicated for the purpose of some stats. >> > > Indeed, I was intending to argue *against* doing it this way. Fundamentally, if > we want to know what's fully mapped and what's not, then I don't see any way > other than by scanning the page tables and we might as well do that in user > space with this script. > > Although, I expect you will shortly make a proposal that is simple to implement > and prove me wrong ;-) Unlikely :) As you said, once you have multiple folio sizes, it stops really making sense. Assume you have a 128 kiB pageache folio, and half of that is mapped. You can set cont-pte bits on that half and all is fine. Or AMD can benefit from it's optimizations without the cont-pte bit and everything is fine. We want simple stats that tell us which folio sizes are actually allocated. For everything else, just scan the process to figure out what exactly is going on. -- Cheers, David / dhildenb