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b=c0wqFhLSzumL/OqPVbXtDtiizPalO/h0r5DGPjU7oar+NwxCyFoB85yznz0RpcjbV oOVPNlCz8+BYqDNziaw7p+V/YPTFeBTHdq7QmA0xvLJhQmy391sXlptl/YwqBg1yFy ygBkaBxZCYX4+wckU7C7SGe2N+4/4NSVzyY8ogVzeCJBZ7c9NaTjlhhhvzdpo+oO32 nqTTdSy4BBbNZXaf6fE22dGE4qb6NkQoshHQ7GqKmP0U9elaVKCEjLr9E6IcedI9Rs DsEmNQG74Gg1n1Uu19FekKfzihoMfHu92RORquyyl8bif1R5AojphHltIwTTQwq8QY r4y21ZPFq0CUQ== Message-ID: Date: Wed, 18 Feb 2026 14:29:44 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [REGRESSION] mm/mprotect: 2x+ slowdown for >=400KiB regions since PTE batching (cac1db8c3aad) To: Luke Yang , dev.jain@arm.com Cc: jhladky@redhat.com, akpm@linux-foundation.org, Liam.Howlett@oracle.com, willy@infradead.org, surenb@google.com, vbabka@suse.cz, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspam-User: X-Rspamd-Queue-Id: 2B4AC1C000F X-Stat-Signature: a1izxeow8mcrxdcdzugni69dd9xu7jpc X-HE-Tag: 1771421391-731558 X-HE-Meta: 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 qRv0xaVU OoIlIFedQ3bamNmgQksiHToNYAopL/jeYqW/1TPioR6rXoNQFD0a2bJpQzszK9z8o+c9KM9ADul3bVNvgozCV0rzB+kLk+vLEh7s7p7UR79jfaj2Fd9s6ysDv9ooznw2PxWH7zB6DPzMhFusDgqkWpDiFoD38CoFzByOZfbSLcM42Mn3Hc+YG0CLEk1dKMcBMMwmjN/9dCMP32k8CLEq9wVDtb7Lt9R5WMmYHfoWlOuXxlZaELyXQVQcMtX6Ahh1o+h3h 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: > int main(int argc, char **argv) > { > int i, j, ret; > long long k; > > if (argc < 4) { > printf("USAGE: %s region_size_kib region_count iterations\n", argv[0]); > printf("Creates multiple regions and times mprotect() calls\n"); > return 1; > } > > long region_size = atol(argv[1]) * 1024L; > int region_count = atoi(argv[2]); > int iterations = atoi(argv[3]); > > int pagesize = sysconf(_SC_PAGESIZE); > > vchar_t **regions = malloc(region_count * sizeof(vchar_t*)); > if (!regions) { > perror("malloc"); > return 1; > } > > for (i = 0; i < region_count; i++) { > regions[i] = (vchar_t *) mmap(NULL, region_size, > PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0L); > I assume that the regression might be more pronounced with MAP_SHARED, because there we really didn't ever required the page/folio during mprotect() IIRC. -- Cheers, David