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Howlett" , linux-mm@kvack.org, linux-doc@vger.kernel.org, Huan Yang , Wang Xiao References: <20261106034841.233085-1-xu.xin@linux.dev> <2a642af6-b97a-4f24-9889-1844812de4cc@huawei.com> 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: 8bit X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam09 X-Stat-Signature: ei16k9cypdadfgzcdpow1fb63aebm9yf X-Rspamd-Queue-Id: 80915A0005 X-Rspam-User: X-HE-Tag: 1794247015-847837 X-HE-Meta: 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 jimlnLaE cPZ+vSB1ckuD3pKFbP9unAcdMyZNRrOXZRr5UvE79b7szsILGjUiaY4n1X7QoVXyaCCnBoodZi4SmuAKC0dgChobXROmxSBYqjPvv0eGcRNNNhdmqq1Ij8lv4y6wykXHpa/OTtoWriJGfvq3Tb6sDOq6eti95D4yXTRe3OVX/EQWj7mMJSJFc/Q22zaG3YdzJ60eLGFsnQU5F3EaNUrklYCoqMEaNOdNEHuszZclMz0YLqjcaF66bLTfJv9+lG6ygx5yYWoOu+DT+DGJ5JJyATNrwYhJWUjP6jQFiHPP4mpGK0ne1/bI0ZVjKusvmvYulzqB7bLWygPsw2ks= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/9/26 03:02, Xu Xin (vivo) wrote: > On Sat, Nov 07, 2026 at 04:13:40PM +0800, Jinjiang Tu wrote: >> >> 在 2026/11/6 11:48, xu.xin@linux.dev 写道: >>> From: "Xu Xin (vivo)" >>> >>> KSM side-channel exposure is desired. Many handset vendors may prefer >>> this knob, which can be used as a default fallback policy. >>> >>> - Not suitable for server and virtualization workloads containing many >>> non-zero duplicate pages, where vanilla KSM provides better memory >>> savings. >> >> It’s a coincidence that I’m also working on similar optimizations. >> In our scenario, we have a MySQL instance with over 700 GB of anonymous >> memory. Most of this memory belongs to the buffer pool, which caches >> data from storage; these pages cannot be merged. Of the remaining memory, >> around 15 GB is consumed by hashtables, which contain many zero-filled >> pages that are eligible for merging to reduce memory footprint. >> >> When we enabled KSM for the entire MySQL instance, ksmd created rmap_item >> metadata for each candidate page.The massive metadata overhead wiped out >> any gains from page merging, and even resulted in a negative benefit. >> >> For this reason, I’m trying to make ksmd merge only zero pages. The goal >> is to have ksmd skip scanning non-zero pages entirely, thereby avoiding >> the rmap_item metadata cost introduced by scanning non-mergeable pages. > > Skip generating ksm_rmap_item for non-zero pages ? That dose make sense to me. Yes, we should avoid any such memory overhead in that case. -- Cheers, David