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[2003:cb:c717:a000:d4df:4b8f:37d4:59e4]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-421270a30e6sm52501855e9.34.2024.05.31.04.13.49 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 31 May 2024 04:13:49 -0700 (PDT) Message-ID: <502fb3df-b42b-4f0c-a98d-348c3d544721@redhat.com> Date: Fri, 31 May 2024 13:13:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 0/6] add mTHP support for anonymous shmem To: Baolin Wang , akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, wangkefeng.wang@huawei.com, ying.huang@intel.com, 21cnbao@gmail.com, ryan.roberts@arm.com, shy828301@gmail.com, ziy@nvidia.com, ioworker0@gmail.com, da.gomez@samsung.com, p.raghav@samsung.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: 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-Rspam-User: X-Stat-Signature: kiscb9mnyrinpj3jdspufkm1cdsogqae X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 4B27F180014 X-HE-Tag: 1717154036-83500 X-HE-Meta: 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 hRrbcrqF izGoQr5aYwtC4uzieHkxq8isdV+lJRMLo3OXGkZ1GfvtgJ6ev3CWcQK5QvssQkYvp31+lFZ9nFfj0tzqUGZW6GTK90nlJrd3thi1Yn8HDxXc8loGuw2J14h6DJZA1fO8JiBbrklKRXAxfrm7hlnap2nvfX76253jVFRZoaV07TcwazYfn/wcyQ0y5vHac0xOyG2ovWhGB8mzGDHR6Ca6sRoG7M3ZEKOp7UWLE7clXyC/0SS4BpyJfkIFb3wuIN4asyBw2dnAWgFZNXEzcarOIVC0z2zTxL409NhT8XkFY7H4oKVQojWA3RULKhLVRKzJNVqv2dP7UEXQq7FNRZ1OREUJM0LwtKjOOCAtefpMZ6knxeGmADwz8DFCYWWWcZpHde6VFQ7S25I7UPrkTIILdXZa0uVITYM52t2pZs9LsGYHZubA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: >> >> As a default, we should not be using large folios / mTHP for any shmem, >> just like we did with THP via shmem_enabled. This is what this series >> currently does, and is aprt of the whole mTHP user-space interface design. >> >> Further, the mTHP controls should control all of shmem, not only >> "anonymous shmem". > > Yes, that's what I thought and in my TODO list. Good, it would be helpful to coordinate with Daniel and Pankaj. > >> >> Also, we should properly fallback within the configured sizes, and not >> jump "over" configured sizes. Unless there is a good reason. >> >> (3) khugepaged >> >> khugepaged needs to handle larger folios properly as well. Until fixed, >> using smaller THP sizes as fallback might prohibit collapsing a >> PMD-sized THP later. But really, khugepaged needs to be fixed to handle >> that. > >> (4) force/disable >> >> These settings are rather testing artifacts from the old ages. We should >> not add them to the per-size toggles. We might "inherit" it from the >> global one, though. > > Sorry, I missed this. So I thould remove the 'force' and 'deny' option > for each mTHP, right? Yes, that's my understanding. But we have to keep them on the top level for any possible user out there. > >> >> "within_size" might have value, and especially for consistency, we >> should have them per size. >> >> >> >> So, this series only tackles anonymous shmem, which is a good starting >> point. Ideally, we'd get support for other shmem (especially during >> fault time) soon afterwards, because we won't be adding separate toggles >> for that from the interface POV, and having inconsistent behavior >> between kernel versions would be a bit unfortunate. >> >> >> @Baolin, this series likely does not consider (4) yet. And I suggest we >> have to take a lot of the "anonymous thp" terminology out of this >> series, especially when it comes to documentation. > > Sure. I will remove the "anonymous thp" terminology from the > documentation, but want to still keep it in the commit message, cause I > want to start from the anonymous shmem. For commit message and friends makes sense. The story should be "controls all of shmem/tmpfs, but support will be added iteratively. The first step is anonymous shmem." -- Cheers, David / dhildenb