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[91.12.99.157]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-438bd47f269sm143800015e9.8.2025.01.27.11.07.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Jan 2025 11:07:21 -0800 (PST) Message-ID: Date: Mon, 27 Jan 2025 20:07:19 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Direct I/O performance problems with 1GB pages To: Jens Axboe , Andres Freund Cc: Matthew Wilcox , linux-mm@kvack.org, linux-block@vger.kernel.org, Muchun Song , Jane Chu , Pavel Begunkov References: <6ulkhmnl4rot5vrywoxvoewko7vbgkhypcwxjccghdu26kwsx5@bnseuzrsedte> <108b6ae7-a272-482b-b3da-60f1fc6617ee@kernel.dk> 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: <108b6ae7-a272-482b-b3da-60f1fc6617ee@kernel.dk> X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 3sZU3Q1WVtwcRuIRUVqTasuJL1gLl5nix8UeTWHP4PY_1738004843 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: 7B3A1A0008 X-Stat-Signature: k1p1y117yosyidj4ezg6brnbkxma3uyg X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1738004846-181842 X-HE-Meta: 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 7tJOlnAf Gp0NUrUsySpVvmWKZEFnf5MtJVfgZ2VDEzSRaPg2ELYL+QAt0Ebqn/ssF3F6w4ypeRL/xRfW7+Kij1f06BZDHw5vRfeb8jhs83uASVBgxrvNQiekrJ29mzjtfmu/mloCnrjVU3OGtjWPdL3LIRbtADles7s3XpXEtvmicdNl9t6NGCk1536flNlqAUzpCnL/W+DdsYHUmYBgNwbKynEog4KJQ9pwFJhlrXvE0QdBI3aiEBrSSmioULr7wlpu7wla/kHoLWnzuvL/bESy1lS+hnA4jbMyUEMakQRl2lqpzZrhmfi2H9dON05ZqdwKt6mX5LMpK30GfK0UL4TM/uZqwjxHyEFQ3B5kS2XQSZN/ObMaN9agQjZzKHc3QtETzgOsC+Plyelpr+mv7iBVpnRUVUIRmSj6fsQgWbONtKEhV8c4dWiyfVhL2O6bUjpiMqI46HzyumNfha115GiN/+WJyjbklAdgK2caGP4ap 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 27.01.25 19:54, Jens Axboe wrote: > On 1/27/25 11:21 AM, Andres Freund wrote: >>> That's precisely what io-uring fixed buffers do :) >> >> I looked at using them at some point - unfortunately it seems that there is >> just {READ,WRITE}_FIXED not {READV,WRITEV}_FIXED. It's *exceedingly* common >> for us to do reads/writes where source/target buffers aren't wholly >> contiguous. Thus - unless I am misunderstanding something, entirely plausible >> - using fixed buffers would unfortunately increase the number of IOs >> noticeably. >> >> Should have sent an email about that... >> >> I guess we could add some heuristic to use _FIXED if it doesn't require >> splitting an IO into too many sub-ios. But that seems pretty gnarly. > > Adding Pavel, he's been working on support registered buffers with > readv/writev. > >> I dimly recall that I also ran into some around using fixed buffers as a >> non-root user. It might just be the accounting of registered buffers as >> mlocked memory and the difficulty of configuring that across >> distributions. But I unfortunately don't remember any details anymore. > > Should just be accounting. For hugetlb we might be able to relax the accounting restriction. It's effectively mlocked already, and setting up hugetlb requires privileges. -- Cheers, David / dhildenb