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 C2474C5478C for ; Fri, 1 Mar 2024 16:44:43 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 55A9D6B0078; Fri, 1 Mar 2024 11:44:43 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 50A046B007B; Fri, 1 Mar 2024 11:44:43 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3AAF66B007E; Fri, 1 Mar 2024 11:44:43 -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 268FB6B0078 for ; Fri, 1 Mar 2024 11:44:43 -0500 (EST) Received: from smtpin14.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id F3866A1C5E for ; Fri, 1 Mar 2024 16:44:42 +0000 (UTC) X-FDA: 81849044004.14.C827D8A Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by imf22.hostedemail.com (Postfix) with ESMTP id C5B20C0022 for ; Fri, 1 Mar 2024 16:44:40 +0000 (UTC) Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=LbO7vHkk; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf22.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=1709311480; 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=CVOB3zsRpP/eqNXRbl971io0eLiYJ7eNMF42L97pkSA=; b=8OKvxgmo58NzLv2NYRzU59Y44P+TULBILCKg3sW4kWBNQe+HivKQX3soqXkHHnjbRN/0WC kPu6hH5aRhLMM2Z37NCdSLHPcTYP7jo3xE05zJ3S8ONu9J3OyAXjkJcigJjcmrRNQS4DoD yXwp6OHok8pks9R1Tk70tjd3Bt597bs= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=LbO7vHkk; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf22.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=1709311480; a=rsa-sha256; cv=none; b=6G05JtWWTbEGwmGyySV3DHDIBwSJyRLGsCxomM7NeIguLBYncgDyIvJbI32LRE2JgtVtu3 ZsjklmUbOzl+khOpKB/rmPW+TrIQLYNnGlqovrzjKOh9yWIf6coHwk9HH8zTy/ZTFbXmst gNGjLD3UeZjiZu9cmKoB9QHLFAHp+h8= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1709311480; 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=CVOB3zsRpP/eqNXRbl971io0eLiYJ7eNMF42L97pkSA=; b=LbO7vHkkvq4pojDmzTQe03BY/Nwzm6w6DgnyaOA0pT+ceQUCN+OG8BsJlvnZDCx1RlWp8V ilGKMTWXezHXeq1crDGRxsJA1WlI7ZfO7n6GdyGZk03J1IEFnnK+GfKUh12QFkrBUjnAfP hvUSa8Bfllr/H+XK4Xh3eckG2pbOy1M= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-389-WdKqDHzaOCyN4Zvu3VhwMQ-1; Fri, 01 Mar 2024 11:44:36 -0500 X-MC-Unique: WdKqDHzaOCyN4Zvu3VhwMQ-1 Received: by mail-wm1-f70.google.com with SMTP id 5b1f17b1804b1-412cf2929fbso158075e9.0 for ; Fri, 01 Mar 2024 08:44:36 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1709311475; x=1709916275; 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=CVOB3zsRpP/eqNXRbl971io0eLiYJ7eNMF42L97pkSA=; b=R1fYShjDJ5CLQCc2IHs8q8wjvEDY5k+CnrrvXY3EAw56mFgUG0toS2LqWpD0W5tONj 8QTCxjDzUTeIZIkgBO69h/UOSOszsLsF+lC9MB3zoj6ibgZ0hq5NdWf0Dr6X2qRn22AQ q0kcJQDSble4mo2Ou2XMFOa3yI6ivDV1rAaS7EIMDS+tzx7SgHhVEk8MRekF6s3T67cL ryepnJpqO9b4wZLm1AEv2kjwyFKSVunEOM74jouOlgQY8kcVTEgVTT8lKEjpBGJezRWF 9v1LOAvZy2OUvtvZ96qPzjB6VHmLHKzH60RCzMvjaaLPmGmC3L45QWF+qVsuDMEVSSW9 JpMg== X-Forwarded-Encrypted: i=1; AJvYcCX2V1c+J5br3MHLWd4w1BCbDT/CR1bcyeRig91PExTBGu5MysupnKyJ4+8a0t05DCSjMVDepH+TCFt6FnvIpynxJXY= X-Gm-Message-State: AOJu0Ywd7SHRCsd2dgBpSpjDdVFNFVnN60rBKx/9Nc4wCGO/IVZ71J00 YFfQAll6qXlxyVLPrtwgm0po/3p0DKej+bl+K0ljpTkAVMrLKinMj7SgNp7nSnHMJIKxP1rGATP N/2K9xgl+7PdQm6ghxn2xWXC0wDgaByzrWRBkb/Iu3GEYHla1 X-Received: by 2002:a05:600c:5493:b0:412:bef2:5a5 with SMTP id iv19-20020a05600c549300b00412bef205a5mr2003591wmb.16.1709311475296; Fri, 01 Mar 2024 08:44:35 -0800 (PST) X-Google-Smtp-Source: AGHT+IHSsmFlxoIysCRqPuhUHYwN6JUc0/78QTi8e6CRwW/POsnANuyWSrDSYCgo/8hF+OlhJd9aYg== X-Received: by 2002:a05:600c:5493:b0:412:bef2:5a5 with SMTP id iv19-20020a05600c549300b00412bef205a5mr2003581wmb.16.1709311474943; Fri, 01 Mar 2024 08:44:34 -0800 (PST) Received: from ?IPV6:2003:cb:c713:3200:77d:8652:169f:b5f7? (p200300cbc7133200077d8652169fb5f7.dip0.t-ipconnect.de. [2003:cb:c713:3200:77d:8652:169f:b5f7]) by smtp.gmail.com with ESMTPSA id u21-20020a7bc055000000b004129a1097e7sm8890274wmc.12.2024.03.01.08.44.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 01 Mar 2024 08:44:34 -0800 (PST) Message-ID: <869455f4-5acc-4699-b53b-e85e19c08458@redhat.com> Date: Fri, 1 Mar 2024 17:44:33 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [LSF/MM/BPF TOPIC] Hugetlb Unifications To: Muchun Song , Matthew Wilcox Cc: James Houghton , Peter Xu , lsf-pc@lists.linux-foundation.org, linux-mm@kvack.org References: <44708637-2258-4AA0-97C1-77BC7EDEEE63@linux.dev> 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: <44708637-2258-4AA0-97C1-77BC7EDEEE63@linux.dev> 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-Rspam-User: X-Stat-Signature: swezwwfh1ifyomqa1jdz7s1mt74ezpad X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: C5B20C0022 X-HE-Tag: 1709311480-981277 X-HE-Meta: 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 C5CdSUmy SLW1aXaQ9MmRAnFCBh+Jqo0GRSCYlahCT8Xx5aH9mmL3M1grF5ZnGeQY4c0+hKUDzQR5VwsLJmnoyrrNEhb2iKEC3rOqfvMEFKcCykqt58bl5YSKSoxlQwxgUke/BR08cp6OTGiBzy1P9mmYvVUBCEUyhxoO0mf0NiaM8 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 01.03.24 07:51, Muchun Song wrote: > > >> On Mar 1, 2024, at 12:29, Matthew Wilcox wrote: >> >> On Thu, Feb 29, 2024 at 05:37:23PM -0800, James Houghton wrote: >>> - It has HVO (which can hopefully be dropped in a memdesc world) >> >> I've spent a bit of time thinking about this. I'll keep this x86-64 >> specific just to have concrete numbers. >> >> Currently a 2MB htlb page without HVO occupies 64 * 512 = 32kB. With HVO, >> it's reduced to 8kB. A 1GB htlb page occupies 64 * 256k = 8MB, with HVO, >> it's still 8kB (right?) > > Correct in the past. In the first version, HVO needs 2 pages (8k) for > vmemmap, however, it only needs only one page (4k) for it whatever the > huge page sizes (2MB or 1GB) now. > >> >> In a memdesc world, a 2MB page without HVO consumes 8 * 512 = 4kB. >> There's no room for savings here. But a 1GB page takes 8 * 256k = 2MB. >> There's still almost 2MB of savings to be had here, so I suspect some >> people will still want it. > > Agree. With 2MB pages, there is no savings with HVO, but it saves a lot > for 1GB huge pages. > >> >> Hopefully Yu Zhao's zone proposal lets us enable HVO for THP. At least >> 1GB ones. > > Hopefully see it. What's the biggest blocker regarding HVO+THP? I can imagine the following two: 1) PMD->PTE remapping currently always has to work. Once we have PTE mappings we would try writing per-page subpage + PAE, which we can't. 2) THP split + freeing would require allocating memory to remap the vmemmap. Split can fail for other reasons already, but the freeing side is nasty. But, if everything fails, we could have memory from the THP itself when hadning it back to the buddy (suboptimal, but removes that corner-case concern). Likely there are other page flags (MCE) that also need care, but at least for hugetlb we seem to have figured that out. -- Cheers, David / dhildenb