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(p200300cbc7078f0043b0110757d228ee.dip0.t-ipconnect.de. [2003:cb:c707:8f00:43b0:1107:57d2:28ee]) by smtp.gmail.com with ESMTPSA id n18-20020ad444b2000000b0067169e210b3sm458681qvt.70.2023.10.31.04.58.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 31 Oct 2023 04:58:54 -0700 (PDT) Message-ID: Date: Tue, 31 Oct 2023 12:58:50 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 0/9] variable-order, large folios for anonymous memory To: Ryan Roberts , Andrew Morton , Matthew Wilcox , Yin Fengwei , Yu Zhao , Catalin Marinas , Anshuman Khandual , Yang Shi , "Huang, Ying" , Zi Yan , Luis Chamberlain , Itaru Kitayama , "Kirill A. Shutemov" , John Hubbard , David Rientjes , Vlastimil Babka , Hugh Dickins Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org References: <20230929114421.3761121-1-ryan.roberts@arm.com> <6d89fdc9-ef55-d44e-bf12-fafff318aef8@redhat.com> <7a3a2d49-528d-4297-ae19-56aa9e6c59c6@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: <7a3a2d49-528d-4297-ae19-56aa9e6c59c6@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: 8545814000B X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: 1ydsc9fwunp8i78uh8hu5hyfnz5kztmp X-HE-Tag: 1698753537-581109 X-HE-Meta: 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 BbuCmpef 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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 31.10.23 12:50, Ryan Roberts wrote: > On 06/10/2023 21:06, David Hildenbrand wrote: > [...] >> >> Change 2: sysfs interface. >> >> If we call it THP, it shall go under "/sys/kernel/mm/transparent_hugepage/", I >> agree. >> >> What we expose there and how, is TBD. Again, not a friend of "orders" and >> bitmaps at all. We can do better if we want to go down that path. >> >> Maybe we should take a look at hugetlb, and how they added support for multiple >> sizes. What *might* make sense could be (depending on which values we actually >> support!) >> >> >> /sys/kernel/mm/transparent_hugepage/hugepages-64kB/ >> /sys/kernel/mm/transparent_hugepage/hugepages-128kB/ >> /sys/kernel/mm/transparent_hugepage/hugepages-256kB/ >> /sys/kernel/mm/transparent_hugepage/hugepages-512kB/ >> /sys/kernel/mm/transparent_hugepage/hugepages-1024kB/ >> /sys/kernel/mm/transparent_hugepage/hugepages-2048kB/ >> >> Each one would contain an "enabled" and "defrag" file. We want something minimal >> first? Start with the "enabled" option. >> >> >> enabled: always [global] madvise never >> >> Initially, we would set it for PMD-sized THP to "global" and for everything else >> to "never". > > Hi David, Hi! > > I've just started coding this, and it occurs to me that I might need a small > clarification here; the existing global "enabled" control is used to drive > decisions for both anonymous memory and (non-shmem) file-backed memory. But the > proposed new per-size "enabled" is implicitly only controlling anon memory (for > now). Anon was (way) first, and pagecache later decided to reuse that one as an indication whether larger folios are desired. For the pagecache, it's just a way to enable/disable it globally. As there is no memory waste, nobody currently really cares about the exact sized the pagecache is allocating (maybe that will change at some point, maybe not, who knows). > > 1) Is this potentially confusing for the user? Should we rename the per-size > controls to "anon_enabled"? Or is it preferable to jsut keep it vague for now so > we can reuse the same control for file-backed memory in future? The latter would be my take. Just like we did with the global toggle. > > 2) The global control will continue to drive the file-backed memory decision > (for now), even when hugepages-2048kB/enabled != "global"; agreed? That would be my take; it will allocate other sizes already, so just glue it to the global toggle and document for the other toggles that they only control anonymous THP for now. -- Cheers, David / dhildenb