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[2003:cb:c70a:be00:a285:bc76:307d:4eaa]) by smtp.gmail.com with ESMTPSA id n12-20020a05600c500c00b00416c160ff88sm630884wmr.1.2024.04.09.11.44.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 09 Apr 2024 11:44:49 -0700 (PDT) Message-ID: <1b20a4cb-42a4-4c50-b1e2-e08104bea1b3@redhat.com> Date: Tue, 9 Apr 2024 20:44:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [LSF/MM/BPF TOPIC] Multi-sized THP performance benchmarks and analysis on ARM64 To: Yang Shi Cc: "Christoph Lameter (Ampere)" , Jonathan Cameron , lsf-pc@lists.linux-foundation.org, olivier.singla@amperecomputing.com, Linux MM , Michal Hocko , Dan Williams References: <20240401191614.00007c83@Huawei.com> <9b3c2d48-96f2-4d29-b2ba-a0f2ea47da45@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: 8bit X-Rspamd-Queue-Id: AA05F40016 X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: ubsfcn1oc6uuqksfxg9ggjmcrfama8co X-HE-Tag: 1712688296-487501 X-HE-Meta: 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 kLO0t+QV PYuzu0m/6uh7ENyPw1PRpoXdOL1IPbOnkibBmhe+oaLnLtlT6Ql6ydPzOiZq493M7/7axa95V3hPuhcrFffbo4tB6TwFq763sg49UvPCJmrcCCchS+yFi3frFYaUik11WuaGMtD/xEceCiRgxLkGYjdtF/fGZLYbjLPmiA4PQord/02Yi/CCCJN4+17vAawe1y8tVOaHA9Jz030CLXP9Ha4CP6TpF9ZpZJNKI3rGQVvXa/OkggtrutqaNBM+Mu/T9JPa3IA0rSOOnqURpM7VsLSA50ldg+I3/rMilQ7E/n0jeOSOd3A6UrHb454FGzan2RJB3FJ0nqe5yLRxRwiQAZFj5VLUzX50gLMPcz9t1PZhLPgZsa/YmHa2CvqHMMRfWXK//0TdvjSYlxYVCG/ELwX4N9Z9HZp28hqTB/xjb7sDxI9xZEHRfw89+dut4SlDeLt/NHUeM+W9/05P6yxXQIRpfrg== 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 09.04.24 20:41, Yang Shi wrote: > On Thu, Apr 4, 2024 at 12:34 PM David Hildenbrand wrote: >> >> On 04.04.24 20:57, Christoph Lameter (Ampere) wrote: >>> On Mon, 1 Apr 2024, Jonathan Cameron wrote: >>> >>>> Sounds like useful data, but is it a suitable topic for LSF-MM? >>>> What open questions etc is it raising? >>> >>> >>> mTHP is new functionality that will require additional work to support >>> more use cases. It is also unclear at this point in what usecases mTHP is >>> useful and where no benefit can so far be seen. Also the effect of >>> coalescing multiple PTE entries into one TLB entry is new to MM >>> (CONT_PTE). >>> >>> Ultimately it would be useful to have mTHP support also provide larger >>> blocksize capabilities for filesystem etc etc. mTHP needs to mature and an >>> analysis of the arguable a bit experimental state of affairs can help a >>> lot in getting there. >> >> Right, something like that (open items, missed use cases, requirements, >> ideas, etc,.) would be a better (good!) fit. >> >> Pure benchmark results, analysis and recommendations are great. But >> likely a better fit for a (white) paper, blog post, >> less-discussion-focused conference. > > Thanks for the suggestion. I didn't plan to enumerate any open items > because I think those items (for example, khugepaged support, swap, > etc) were already well-known by mm community and we have made some > progress on some items. I think there are two types of open items: "we obviously know what we have to do -- basic swap, khugepaged, etc. support" and "we don't really know what to do because it's rather an optimization problem and there might not be a right or wrong". > > The potential future optimization choices led by the benchmark and > analysis may be worth discussing. For example, shall the allocation > fallback should try every single order, is it a good idea to let users > decide the orders, etc. We didn't know what the good choice should be > before we had some benchmark data. Focusing on such open questions makes a lot of sense. Then, you can use the benchmark data to guide the discussion and share your insights :) -- Cheers, David / dhildenb