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b=IHzAQTxEzZjfnpsSIqAAD4fPesFDb3+Zx7cbefp+ZKkpbBelTRXZv7Q/s8qIJvXsh ivmojcdkTW5ri8U34lOS1edOIvsqMkJxNqok/USQBLXU09hQR57dSR4N2ZFYPV1n2d iPfVdjA7ak5SpL7tp9O1xTISPO3LV/IENkzEdnRxfvoVWumq2xnNwKnRxgSxexW+KN 7NGpry0Ka0TafkQCwNN+KJx6QpPoOgLWnGyUmA9Ph/bS33cDPcU0GjRg9azm2gX5n/ B3+PQgOYM83dPUDnZOQJtBmOXLluCr54oD1N7cArc66bnd9zRolHvxZqqAsK/zspwJ PvbHN0Nl+tErQ== Message-ID: <3b16e616-5104-4559-95d4-2942173561e8@kernel.org> Date: Mon, 2 Mar 2026 09:52:56 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm: add Adaptive Memory Pressure Signaling (AMPRESS) To: Andre Ramos , akpm@linux-foundation.org, hannes@cmpxchg.org Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, rostedt@goodmis.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 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: D79B340007 X-Stat-Signature: 65zm4pzik1eshkb7btxixe9biarcnohd X-Rspam-User: X-HE-Tag: 1772441581-890231 X-HE-Meta: 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 Ypxb8Iua ZY/C5TUiY+1WO8f9Jj38+zHX4gKVYLMelM3bjAGIZyKN4BpF3DXUL2ft+co7J0WoqYD8l0VimBHXheYdXAchT4CRclrFf5r/7KAlmjnkqjK39FHDAoy1Dwpu3jCXWH4D91a2jWpn/Wp7s1T/zXK17jBl3Mf663G/YWrISjp5QhOlp1gv8XMlzZ2Eed2T9+NEYLjJ+YH5uXlPhegFQoY2wocXkxH+e6txkGA9tfIdXEMhNZZicoyNDYR67b7uoXxAzL61HPX2OebZO0hkhXcOYSjc/KYTQEboQco08LSe0VNjItSfjnP1ypCLd57vmuLeCI3rBC0sxZ3vQP6GSQ/nknad++Q== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 3/2/26 04:45, Andre Ramos wrote: > Introduce /dev/ampress, a bidirectional fd-based interface for > cooperative memory reclaim between the kernel and userspace. I'm very sure this should be tagged as RFC. > > Userspace processes open /dev/ampress and block on read() to receive > struct ampress_event notifications carrying a graduated urgency level > (LOW/MEDIUM/HIGH/FATAL), the NUMA node of the pressure source, and a > suggested reclaim target in KiB. After freeing memory the process > issues AMPRESS_IOC_ACK to close the feedback loop. > > The feature hooks into balance_pgdat() in mm/vmscan.c, mapping the > kswapd scan priority to urgency bands: > priority 10-12 -> LOW > priority 7-9 -> MEDIUM > priority 4-6 -> HIGH > priority 1-3 -> FATAL > > ampress_notify() is IRQ-safe (read_lock_irqsave + spin_lock_irqsave, > no allocations) so it can be called from any reclaim context. > Per-subscriber events overwrite without queuing to prevent unbounded > backlog. A debugfs trigger at /sys/kernel/debug/ampress/inject allows > testing without real memory pressure. [...] > > +ADAPTIVE MEMORY PRESSURE SIGNALING (AMPRESS) > +M: Darabat > +L: linux-mm@kvack.org > +S: Maintained > +F: include/linux/ampress.h > +F: include/trace/events/ampress.h > +F: include/uapi/linux/ampress.h > +F: mm/ampress.c > +F: mm/ampress_test.c > +F: tools/testing/ampress/ We generally don't make new kernel contributors MM maintainers. But what sticks out more is the inconsistency between your name+mail and "Darabat ". -- Cheers, David