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(p200300cbc707240068a392e0906fb69d.dip0.t-ipconnect.de. [2003:cb:c707:2400:68a3:92e0:906f:b69d]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-37ecf027e31sm2557761f8f.12.2024.10.18.11.42.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 18 Oct 2024 11:42:23 -0700 (PDT) Message-ID: <7ec81ff8-5645-42a1-a048-c8700aff07fa@redhat.com> Date: Fri, 18 Oct 2024 20:42:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/1] Buddy allocator like folio split To: Zi Yan , linux-mm@kvack.org, "Matthew Wilcox (Oracle)" Cc: Ryan Roberts , Hugh Dickins , "Kirill A . Shutemov" , Yang Shi , Miaohe Lin , Kefeng Wang , Yu Zhao , John Hubbard , linux-kernel@vger.kernel.org References: <20241008223748.555845-1-ziy@nvidia.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: <20241008223748.555845-1-ziy@nvidia.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-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 327B8A001B X-Stat-Signature: qttw1gtmbu4z5igj1ixxz1y63f7mwe9j X-HE-Tag: 1729276936-553865 X-HE-Meta: U2FsdGVkX18UfmWRHk1L++Meyai01Kn7itBtqyVh4mhdXlDN0s1GN/ZiQGLiXF/B3LN0Br4pBeVRb2qKjQRBcG7jbkQusqZL772NqHew5NVAj65FCjDqR5nebE57go8CLXHgmw1pfTNZmv2KZuZCILL386M+DmKOOr5yYkGseSQWA561bDZwwOkW8v5tvzRUwmDTkPSdMkfLyMhGGlU5POJsAocMK5HLnSJc4pCycgTq9ovxi+5UH3aFGv9OpVkHK+38VW64e70vrvVHGhXjjcMWWgXvj9A/aiAwtdedU7sDiirOmTkvJD95rQVXHHTx4VLRESCXFpkHeuyJy+ioeO87wZUM1/z3fLaKYDGWsdoge9SntH/SazTXBVBAjsnc8Ro+cni8m4sTw9lE3uWY2JLwoXPC5U7Svo4T5UU41Eke4QCii6OJle+/csTXHG19CDdNUWZ2q0vZj09A9Vi4Jv9fPBKZHL1i96iD3sZLjzBBzMw232od8m4dPhA3dJu91b5RJw9ZQAAw20i2teOt37l+W5GFcZoIiaxNASmVrua2q/JjyghNnPbvb+pmn4mqMEzReiit+ZwtahLtQ1RH1xVfXwNLhejQ3UoIDWRU0it11D4fkZnvT0YUEtRwlz3pV7XjF8uUz09BTQWFzU9QsL1sPVSuEb7JZd8WUTjOANNRirANyNvp+169n/dL92Is4Oe2r8g+lz1HhSXUxhc5WrW22jy4B6nRlkz/lfGN7az4XLjA63WTiyVeFHBKD19n+Yn/V4xA52BvlbRCEwStC2yVaI+nfEt+Yjn6Wh93FtMD3evSSkej8xhMK7aB5+ANTh6D6YTutukfW9VQZ1UR+LmMhpm3VtEHXDvBTPK1wBPHdbr72MYk8nlXE5MAQxUJPTtYh1hXaI/IwTs55MPQUVvVdfZQWUD1QFt+A/WxZKstWTejPrwewv9vFcrARt/l1sMZ09s0TDifNUsVViv RtqWc8sw 14zrNYlCAtmIPoKR1pRiu1A7Q0JyD2aqPf35LjdAK9pILJg5Pooi8BgUpjFJGJ6CEmTfZ2WCWjkqPPWW0doccp+qTDRDoSx/yCTliuNjDsXFscH/xqv5DmzcjVC+h7U9MTH2i4thZvD53VgGXZhqknY0sej8OddpudVpJESp6/mmJsF4uJ/nrz6G/285DAXbQDfBIM/MnMdZOdDn8pN9Z0iVRb7Bw8QEzV3aKw/Q4zmA5uskrRWb6ZhllK2UEgJgnoI/Qv6ZmLg1q6hqyEdUu52iw1N0HIyjPr5HUXTtBt+uZBsFh/W2PifYEm6heocAlnddNGHXTMhEBUsw/9EzgKwPw57VG71FJ7aaO4We7wm7b25Mu6wLKlMNMs5WYpD4WkGfWbMyhNPPt2f8= 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 09.10.24 00:37, Zi Yan wrote: > Hi all, Hi! > > Matthew and I have discussed about a different way of splitting large > folios. Instead of split one folio uniformly into the same order smaller > ones, doing buddy allocator like split can reduce the total number of > resulting folios, the amount of memory needed for multi-index xarray > split, and keep more large folios after a split. In addition, both > Hugh[1] and Ryan[2] had similar suggestions before. > > The patch is an initial implementation. It passes simple order-9 to > lower order split tests for anonymous folios and pagecache folios. > There are still a lot of TODOs to make it upstream. But I would like to gather > feedbacks before that. Interesting, but I don't see any actual users besides the debug/test interface wired up. I assume ftruncate() / fallocate(PUNCH_HOLE) might be good use cases? For example, when punching 1M of a 2M folio, we can just leave a 1M folio in the pagecache. Any other obvious users you have in mind? -- Cheers, David / dhildenb