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[2003:cb:c70a:7600:9a0b:ceef:a304:b9a7]) by smtp.gmail.com with ESMTPSA id t18-20020a05600c199200b0040ecea22794sm2375607wmq.45.2024.01.25.04.44.36 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 Jan 2024 04:44:37 -0800 (PST) Message-ID: Date: Thu, 25 Jan 2024 13:44:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Issue] mprotect+madvise may be better than mmap for permission changes and page zeroing To: Lance Yang , linux-kernel@vger.kernel.org Cc: Michal Hocko , linux-mm@kvack.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-Rspamd-Queue-Id: 32DC240027 X-Rspam-User: X-Stat-Signature: iq3pg1q9k9wibf18o315d9m3bq3q8xwo X-Rspamd-Server: rspam03 X-HE-Tag: 1706186681-928977 X-HE-Meta: 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 LgIbZn9C Jo1S1+mFcWPZHqYb7DLEK6vBPXgPBJsdejifh5vuCuT/+OSjrjcdwV8YA3CYPWGRGbxH9hn1SGa0uVdPEMHyhNUQvpn2Z067LXLU/cDcOEOnj1PWDcpQKkKgPhF2To+xNIKIkH5Mnfp2Z/kOQ43/uB9RkPEwfZAhSRCYFoHo+yKM83qkhkE358YsqQ3EbXt67WK+5NZ9j54hiIa7MutDykpG0eh5xsw8aPhMmvH5qUN1bzHQ/03OFaQIgob8j8slpnuRLwR155aNG+QN2AnQBn0dgdGU/LMCrqppqximuCGgYF1tvHrmroDBfneS9tC1pPy8E9hMHazp3Y8PI6Ayw7vZVX6YdXWTdOQgG6+9ppAxZYcHXlOsFnO/6ZAZw3kx6ZF2w/hFp6KzUuIhEICWHiqK6p46iavDN+3SnrdskfTqzPJK4BvJWi+atAZSmpi7ubH501FfQL6diX7ySG//i/UHDt7zC07jdzyNp 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 25.01.24 13:28, Lance Yang wrote: > Hello Everyone, > > I've noticed that using mprotect(PROT_NONE) with > madvise(MADV_DONTNEED) is much faster than > mmap(PROT_NONE, MAP_FIXED) alone for changing > permissions and zeroing pages. > > I have maintained a chunk-allocator internally at the > company. It allocates a chunk using > mmap(PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, -1, 0), > releases a chunk using mmap(PROT_NONE, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0), > and reuses a chunk using mprotect(PROT_READ|PROT_WRITE). > Recently, I replaced mmap(PROT_NONE, MAP_FIXED) with > mprotect(PROT_NONE) + madvise(MADV_DONTNEED) to > reduce the latency of releasing chunks. > > Test code: > https://github.com/ioworker0/mmapvsmprotect/blob/main/test2.c > > Here are the test results on my machine: > CPU: AMD EPYC 7R13 Processor > Kernel: 6.2.0 > Elapsed Time for mprotect+madvise: 3670 nanoseconds > Elapsed Time for mmap: 5520 nanoseconds mprotect+madvise won't free page tables, mmap will. That's the biggest difference. -- Cheers, David / dhildenb