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 5D907C47258 for ; Tue, 23 Jan 2024 19:33:18 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B534A6B007D; Tue, 23 Jan 2024 14:33:17 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B03016B007E; Tue, 23 Jan 2024 14:33:17 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 97DFC6B0080; Tue, 23 Jan 2024 14:33:17 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 88E626B007D for ; Tue, 23 Jan 2024 14:33:17 -0500 (EST) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 2B2B0160B8A for ; Tue, 23 Jan 2024 19:33:17 +0000 (UTC) X-FDA: 81711574434.09.C818B3F Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf29.hostedemail.com (Postfix) with ESMTP id E92A8120003 for ; Tue, 23 Jan 2024 19:33:14 +0000 (UTC) Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=M5tsQB4m; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf29.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1706038395; 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=itYhj3A7U4JKSUVX1BM5+D5uWXBZ/cx6KAiSvHjO3Z4=; b=bz2weeL8PfFbpL++daakauzIs6OwSB1OzgVOlfxtoCrPrbdzZRkgWClr2wQfGh7Alnynpk 2uNRQueFZikLNHdL0fT3HFDaPDudDsGqkyK02g9EwiHOfL15izKS/5dF+cCeqKJLgA6/Ui lMdjErI5eaI/d5zNTRxq8whTdYYlJzU= ARC-Authentication-Results: i=1; imf29.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=M5tsQB4m; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf29.hostedemail.com: domain of david@redhat.com designates 170.10.129.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1706038395; a=rsa-sha256; cv=none; b=sTZZ0jwURa63LO/aYq65fJajqeG1GyINEJK/68R78rHtvhrWYHpKrNuR35Qc6U04jsweDv kpAJ3msF0Zj58ski0hi4A6mYlXgE+vfMv+MZZ7DRPAQpXaLuY9+jqL9tVLEyB+GjD4xE6u eSTJT/3H0IM7LoEHX2Z54AOW/e7K/e0= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1706038394; 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=itYhj3A7U4JKSUVX1BM5+D5uWXBZ/cx6KAiSvHjO3Z4=; b=M5tsQB4myEXy1QSDjWW27l47ZgThzWFZPefuyYc5RxKEE/4FkXXLm7QAF0qZPiH9PSBLpL 0VrCYnU5lllpu5F+o0F4TFfL0tyHfQ469vcQ9iIhckmCvxD5fvin7KW4a42RV+2LAc9HVl yAJ4zmycqR0a75kqGWJdYzZIsi66LZM= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-311-dTXdnAKNMamj1RTASqbg2A-1; Tue, 23 Jan 2024 14:33:12 -0500 X-MC-Unique: dTXdnAKNMamj1RTASqbg2A-1 Received: by mail-wr1-f69.google.com with SMTP id ffacd0b85a97d-337d05db5bbso2817856f8f.3 for ; Tue, 23 Jan 2024 11:33:12 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706038391; x=1706643191; 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=itYhj3A7U4JKSUVX1BM5+D5uWXBZ/cx6KAiSvHjO3Z4=; b=nOpTc+UZ7jIqVaRgaWZEMzm8h10clNIQimk/umAKKmH7I7UPLysnaDipzWRLa8Xfc8 KGjEwIH3vWCfOw/3Bu1PH+hKVci1KZ/oJXk/hJB68ZPksI+YmY42mv2+hK2Hom2DHMJw VHxnpCCId7ceClKl+r3LoIBOqH6oWB6bSypyDbtc/DRNqg2DZTRvCpT79WzoqE0zEzXZ EV0105kM0wu/OipTDJ83Un13GEAjEwk9MjagAQL95Lv1wL43Er6ihrE2dRkwNdZtjwFh G1vXQBUgm2h2L7CIg0xh2zdZPOF3A6+HI/mft7TdudA/ssGye6ivWkR59lBp5fD7etaQ Fnpg== X-Gm-Message-State: AOJu0YxoSb3c1rbSWi9RQV3aNhiTGKS0ek2pUvzEmhSV0JO/H5/TUGUQ dcRga6NemQ4UXFCatNbu/xTbQFwP+jEIcA18ZIxj1xFV0fDotTAiL1TDZAkT7MtevLOcOzVbHEQ LsZXDh2H/5OsQ65/4vA6arORV7PYj+McDNlZ8Smz3MxG6Accw X-Received: by 2002:a05:600c:6a93:b0:40e:b95b:d076 with SMTP id jl19-20020a05600c6a9300b0040eb95bd076mr487977wmb.330.1706038391565; Tue, 23 Jan 2024 11:33:11 -0800 (PST) X-Google-Smtp-Source: AGHT+IGSoUQW9eSU5KRKucbehRTRFWuogFSdzMHtpayE9Ps/dIeIEUdDVdNTw9NHgbZWG2SGW4YMsA== X-Received: by 2002:a05:600c:6a93:b0:40e:b95b:d076 with SMTP id jl19-20020a05600c6a9300b0040eb95bd076mr487958wmb.330.1706038391187; Tue, 23 Jan 2024 11:33:11 -0800 (PST) Received: from ?IPV6:2003:cb:c741:de00:bf0f:cd46:dc1c:2de9? (p200300cbc741de00bf0fcd46dc1c2de9.dip0.t-ipconnect.de. [2003:cb:c741:de00:bf0f:cd46:dc1c:2de9]) by smtp.gmail.com with ESMTPSA id h17-20020a05600c499100b0040d6e07a147sm41857469wmp.23.2024.01.23.11.33.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Jan 2024 11:33:10 -0800 (PST) Message-ID: Date: Tue, 23 Jan 2024 20:33:09 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 00/11] mm/memory: optimize fork() with PTE-mapped THP To: Ryan Roberts , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Andrew Morton , Matthew Wilcox , Russell King , Catalin Marinas , Will Deacon , Dinh Nguyen , Michael Ellerman , Nicholas Piggin , Christophe Leroy , "Aneesh Kumar K.V" , "Naveen N. Rao" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexander Gordeev , Gerald Schaefer , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , "David S. Miller" , linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org References: <20240122194200.381241-1-david@redhat.com> <56bee384-461e-4167-b7e9-4dd60666dd66@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: <56bee384-461e-4167-b7e9-4dd60666dd66@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: 7bit X-Rspamd-Queue-Id: E92A8120003 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: 4zorbt3hsgcb37p6mxfkb9jwn91oez8w X-HE-Tag: 1706038394-28278 X-HE-Meta: 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 nYtabhkF KasASPjcj+4Iz9XsMvlwWHnhZrgUsL1ALtw1lnfGYzerBdxHmQAmIsOfs8p8zTWkaGvlvhgZpMAfxvCiVDJ1JlLLl3tYKTrKXX0gKLnxjzMOXqrNxl1sl3+sx9rb3uwqOcT8GbPcE16er5XNQCd/I1bjs7qMsNYYXZoeHy1CEYzID/BB6qE4yHCguVKB6Dn6BPDkqmi3ViZI9S82ocWa8J1gK1hdGeBibkU0Rqo2DOFcUA4Vm4AV26uwRKHIMqmrIAM/FMDFWzSqvo0tW1mEvOGjZoeR0v1FHCBcFCbSj3pAacaFHlcT3XlkaeaDYZcti3ye+FgmtJxZKLomLnGaSp+c+TUtGo5VWnSTkTZcSQueCk8fT7u4xy6Ny6DwL1RZ6jyV444M4QfgutQXmQE8JExErEXtWwr7jLpCHepCGrJu8Jos= 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 23.01.24 20:15, Ryan Roberts wrote: > On 22/01/2024 19:41, David Hildenbrand wrote: >> Now that the rmap overhaul[1] is upstream that provides a clean interface >> for rmap batching, let's implement PTE batching during fork when processing >> PTE-mapped THPs. >> >> This series is partially based on Ryan's previous work[2] to implement >> cont-pte support on arm64, but its a complete rewrite based on [1] to >> optimize all architectures independent of any such PTE bits, and to >> use the new rmap batching functions that simplify the code and prepare >> for further rmap accounting changes. >> >> We collect consecutive PTEs that map consecutive pages of the same large >> folio, making sure that the other PTE bits are compatible, and (a) adjust >> the refcount only once per batch, (b) call rmap handling functions only >> once per batch and (c) perform batch PTE setting/updates. >> >> While this series should be beneficial for adding cont-pte support on >> ARM64[2], it's one of the requirements for maintaining a total mapcount[3] >> for large folios with minimal added overhead and further changes[4] that >> build up on top of the total mapcount. > > I'm currently rebasing my contpte work onto this series, and have hit a problem. > I need to expose the "size" of a pte (pte_size()) and skip forward to the start > of the next (cont)pte every time through the folio_pte_batch() loop. But > pte_next_pfn() only allows advancing by 1 pfn; I need to advance by nr pfns: > > > static inline int folio_pte_batch(struct folio *folio, unsigned long addr, > pte_t *start_ptep, pte_t pte, int max_nr, bool *any_writable) > { > unsigned long folio_end_pfn = folio_pfn(folio) + folio_nr_pages(folio); > const pte_t *end_ptep = start_ptep + max_nr; > pte_t expected_pte = __pte_batch_clear_ignored(pte_next_pfn(pte)); > - pte_t *ptep = start_ptep + 1; > + pte_t *ptep = start_ptep; > + int vfn, nr, i; > bool writable; > > if (any_writable) > *any_writable = false; > > VM_WARN_ON_FOLIO(!pte_present(pte), folio); > > + vfn = addr >> PAGE_SIZE; > + nr = pte_size(pte); > + nr = ALIGN_DOWN(vfn + nr, nr) - vfn; > + ptep += nr; > + > while (ptep != end_ptep) { > + pte = ptep_get(ptep); > nr = pte_size(pte); > if (any_writable) > writable = !!pte_write(pte); > pte = __pte_batch_clear_ignored(pte); > > if (!pte_same(pte, expected_pte)) > break; > > /* > * Stop immediately once we reached the end of the folio. In > * corner cases the next PFN might fall into a different > * folio. > */ > - if (pte_pfn(pte) == folio_end_pfn) > + if (pte_pfn(pte) >= folio_end_pfn) > break; > > if (any_writable) > *any_writable |= writable; > > - expected_pte = pte_next_pfn(expected_pte); > - ptep++; > + for (i = 0; i < nr; i++) > + expected_pte = pte_next_pfn(expected_pte); > + ptep += nr; > } > > return ptep - start_ptep; > } > > > So I'm wondering if instead of enabling pte_next_pfn() for all the arches, > perhaps its actually better to expose pte_pgprot() for all the arches. Then we > can be much more flexible about generating ptes with pfn_pte(pfn, pgprot). > > What do you think? The pte_pgprot() stuff is just nasty IMHO. Likely it's best to simply convert pte_next_pfn() to something like pte_advance_pfns(). The we could just have #define pte_next_pfn(pte) pte_advance_pfns(pte, 1) That should be fairly easy to do on top (based on PFN_PTE_SHIFT). And only 3 archs (x86-64, arm64, and powerpc) need slight care to replace a hardcoded "1" by an integer we pass in. -- Cheers, David / dhildenb