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(p200300cbc721a0007426f6b482a3c6ab.dip0.t-ipconnect.de. [2003:cb:c721:a000:7426:f6b4:82a3:c6ab]) by smtp.gmail.com with ESMTPSA id f9-20020a0560001b0900b003143867d2ebsm4813981wrz.63.2023.11.24.09.34.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 24 Nov 2023 09:34:11 -0800 (PST) Message-ID: <26c361bc-6d87-4a57-9fae-ef635c9039c7@redhat.com> Date: Fri, 24 Nov 2023 18:34:10 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RESEND PATCH v7 00/10] Small-sized THP for anonymous memory To: Matthew Wilcox Cc: Ryan Roberts , Andrew Morton , 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 , Kefeng Wang , linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20231122162950.3854897-1-ryan.roberts@arm.com> <9c8f6d2a-7ed8-45d2-9684-d77489bd99b8@redhat.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: 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-Stat-Signature: f59xzc61muo47zhbecb94f3hsb7ksen5 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 37824100023 X-Rspam-User: X-HE-Tag: 1700847256-758473 X-HE-Meta: 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 OIzOGWqB 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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 24.11.23 16:53, Matthew Wilcox wrote: > On Fri, Nov 24, 2023 at 04:25:38PM +0100, David Hildenbrand wrote: >> On 24.11.23 16:13, Matthew Wilcox wrote: >>> On Fri, Nov 24, 2023 at 09:56:37AM +0000, Ryan Roberts wrote: >>>> On 23/11/2023 15:59, Matthew Wilcox wrote: >>>>> On Wed, Nov 22, 2023 at 04:29:40PM +0000, Ryan Roberts wrote: >>>>>> This is v7 of a series to implement small-sized THP for anonymous memory >>>>>> (previously called "large anonymous folios"). The objective of this is to >>>>> >>>>> I'm still against small-sized THP. We've now got people asking whether >>>>> the THP counters should be updated when dealing with large folios that >>>>> are smaller than PMD sized. It's sowing confusion, and we should go >>>>> back to large anon folios as a name. >>>> >>>> I suspect I'm labouring the point here, but I'd like to drill into exactly what >>>> you are objecting to. Is it: >>>> >>>> A) Using the name "small-sized THP" (which is currently only used in the commit >>>> logs and a couple of times in the documentation). >>> >>> Yes, this is what I'm objecting to. >> >> I'll just repeat that "large anon folio" is misleading, because >> * we already have "large anon folios" in hugetlb > > We do? Where? MAP_PRIVATE of hugetlb. hugepage_add_anon_rmap() instantiates them. Hugetlb is likely one of the oldest user of compund pages aka large folios. > >> * we already have PMD-sized "large anon folios" in THP > > Right, those are already accounted as THP, and that's what users expect. > If we're allocating 1024 x 64kB chunks of memory, the user won't be able > to distinguish that from 32 x 2MB chunks of memory, and yet the > performance profile for some applications will be very different. Very right, and because there will be a difference between 1024 x 64kB, 2048 x 32 kB and so forth, we need new memory stats either way. Ryan had some ideas on that, but currently, that's considered future work, just like it likely is for the pagecache as well and needs much more thoughts. Initially, the admin will have to enable all that for anon either way. It all boils down to one memory statistic for anon memory (AnonHugePages) that's messed-up already. > >> But inn the end, I don't care how we will call this in a commit message. >> >> Just sticking to what we have right now makes most sense to me. >> >> I know, as the creator of the term "folio" you have to object :P Sorry ;) > > I don't care if it's called something to do with folios or not. I Good! > am objecting to the use of the term "small THP" on the grounds of > confusion and linguistic nonsense. Maybe that's the reason why FreeBSD calls them "medium-sized superpages", because "Medium-sized" seems to be more appropriate to express something "in between". So far I thought the reason was because they focused on 64k only. Never trust a German guy on naming suggestions. John has so far been my naming expert, so I'm hoping he can help. "Sub-pmd-sized THP" is just mouthful. But then, again, this is would just be a temporary name, and in the future THP will just naturally come in multiple sizes (and others here seem to agree on that). But just to repeat: I don't think there is need to come up with new terminology and that there will be mass-confusion. So far I've not heard a compelling argument besides "one memory counter could confuse an admin that explicitly enables that new behavior.". Side note: I'm, happy that we've reached a stage where we're nitpicking on names :) -- Cheers, David / dhildenb