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b=E1q0w0cDwPhOB4LOSqfrUxeF5HN6B0FfC17poneLeKRwHBfHScquG3UD203zHqHjP Qdhqz0Ctjr1uFF/kXy6c+yP8JKhLJ6Ml+n1lHcsu85oCiL9wE7JRHZCHZLhVSwxYoJ xtzWwG7bm+gXJudcH/2V8Ebt/ixxX+OUI8d8Y2kehEBlV2mOTLHqa5fWa00cj7xPkR pdsYcyoULcTrFKrLoBBlCo841df4RR4dO0ETVGv/Osfz0dlW+TVxl70sQLFoljnFRj UE/YVpqYUgDaNVbdyDII+6taRrOJys0/+KcS33CEgCcwslbkpIx9NfhK7QKGUZQvMc 3A5JqaribBaPw== Message-ID: Date: Fri, 13 Feb 2026 16:47:29 +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-Stat-Signature: 4ndryboets948ajhtntob7q9uf9f19ap X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1723F18000F X-HE-Tag: 1770997656-970961 X-HE-Meta: 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 641xS7Wo laryaLryoJIRqf5ta/rkn3SplDH2PfEfkYbROx/YCxxRVibz5mUpg5Qq1UJE6msJWV8NKopFpv6o3EUo7eDnPgHBpTiH3prZmcik7FpYbqKPxGram5+ZmyYQop5zgjaH8VOsbfsOjMIgnnOk4zzo4lFh4w6CH8ZSvI8bsA5xaPicq+3GUBbl3TlMSiDbbS3s7C9bSO4imHCc611MS9BTIuZJmW5NbsjYXfv7HdsF3j8KZbmBHqrB5923PkqPFDHtAL7En 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 2/13/26 16:08, Luke Yang wrote: > Hello, Hi! > > we have bisected a significant mprotect() performance regression in > 6.17-rc1 to: > > cac1db8c3aad ("mm: optimize mprotect() by PTE batching") > > The regression becomes clearly visible starting around 400 KiB region > sizes and above. It is also still present in the latest 6.19 kernel. > Micro-benchmark results are nice. But what is the real word impact? IOW, why should we care? -- Cheers, David