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[2003:cb:c706:fd00:fb07:92f8:8f0c:6a08]) by smtp.gmail.com with ESMTPSA id r7-20020a05600c35c700b0041638a085d3sm23433800wmq.15.2024.04.23.04.05.08 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 23 Apr 2024 04:05:08 -0700 (PDT) Message-ID: <8abcc8aa-473f-4a3c-a528-d32a0c8bfd75@redhat.com> Date: Tue, 23 Apr 2024 13:05:07 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 0/5] add mTHP support for anonymous share pages To: Ryan Roberts , Baolin Wang , akpm@linux-foundation.org, hughd@google.com Cc: willy@infradead.org, wangkefeng.wang@huawei.com, 21cnbao@gmail.com, ying.huang@intel.com, shy828301@gmail.com, ziy@nvidia.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <4b998e7d-153f-48cc-a9bb-8c84bb675581@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: <4b998e7d-153f-48cc-a9bb-8c84bb675581@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-Server: rspam04 X-Rspamd-Queue-Id: 4417140025 X-Rspam-User: X-Stat-Signature: hin3wwzbfz4afy87dzichydushubs1bd X-HE-Tag: 1713870315-624937 X-HE-Meta: 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 WK/sOhXJ Dq0pm2pB+mzYqNrOso0ADnDukGmIvgbROtq9LV4EDyRGpS7PfdTNbLwGalQGWXtTrJ6qElgyWthQyCSIhZZ9iR4zRb+yJhqaAI1s60aYye/IDlBY7Y4YLUH6+7eYFLAJX5aJysq1NbgMWCO8lBrt8YVqzHsg8w6wZM6kGY0+pcwVMf8dup+8BKgBuC29UMBCbEyLRYE2vw1TSW8RJ1V62y6XZSRP0m7YZ5wqAU1e/uALeJsCFo8Ogroe0HNu7FYkcDRGTOONYB7fpsM1ucvdwOBAVI+Tfx0CSZ/grWyJHpnpAuMjkwLU3LwbfO4Ot6UE9CL0p/K74Ws9Lfv8gt8popizhLPOswNrj5rQgx/b5XGkL6zYh20tgdY2IRsiK0GaLiIlVjhwmNPkcsGn8cT0S60h2v6lwEnqr3Tzd9a57VfXWeio= 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 23.04.24 12:41, Ryan Roberts wrote: > On 22/04/2024 08:02, Baolin Wang wrote: >> Anonymous pages have already been supported for multi-size (mTHP) allocation >> through commit 19eaf44954df, that can allow THP to be configured through the >> sysfs interface located at '/sys/kernel/mm/transparent_hugepage/hugepage-XXkb/enabled'. >> >> However, the anonymous shared pages will ignore the anonymous mTHP rule >> configured through the sysfs interface, and can only use the PMD-mapped >> THP, that is not reasonable. Many implement anonymous page sharing through >> mmap(MAP_SHARED | MAP_ANONYMOUS), especially in database usage scenarios, >> therefore, users expect to apply an unified mTHP strategy for anonymous pages, >> also including the anonymous shared pages, in order to enjoy the benefits of >> mTHP. For example, lower latency than PMD-mapped THP, smaller memory bloat >> than PMD-mapped THP, contiguous PTEs on ARM architecture to reduce TLB miss etc. > > This sounds like a very useful addition! > > Out of interest, can you point me at any workloads (and off-the-shelf benchmarks > for those workloads) that predominantly use shared anon memory? > >> >> The primary strategy is that, the use of huge pages for anonymous shared pages >> still follows the global control determined by the mount option "huge=" parameter >> or the sysfs interface at '/sys/kernel/mm/transparent_hugepage/shmem_enabled'. >> The utilization of mTHP is allowed only when the global 'huge' switch is enabled. >> Subsequently, the mTHP sysfs interface (/sys/kernel/mm/transparent_hugepage/hugepage-XXkb/enabled) >> is checked to determine the mTHP size that can be used for large folio allocation >> for these anonymous shared pages. > > I'm not sure about this proposed control mechanism; won't it break > compatibility? I could be wrong, but I don't think shmem's use of THP used to > depend upon the value of /sys/kernel/mm/transparent_hugepage/enabled? So it > doesn't make sense to me that we now depend upon the > /sys/kernel/mm/transparent_hugepage/hugepage-XXkb/enabled values (which by > default disables all sizes except 2M, which is set to "inherit" from > /sys/kernel/mm/transparent_hugepage/enabled). > > The other problem is that shmem_enabled has a different set of options > (always/never/within_size/advise/deny/force) to enabled (always/madvise/never) > > Perhaps it would be cleaner to do the same trick we did for enabled; Introduce > /mm/transparent_hugepage/hugepage-XXkb/shmem_enabled, which can have all the > same values as the top-level /sys/kernel/mm/transparent_hugepage/shmem_enabled, > plus the additional "inherit" option. By default all sizes will be set to > "never" except 2M, which is set to "inherit". Matches what I had in mind. -- Cheers, David / dhildenb