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Howlett" , David Hildenbrand , Jonathan Corbet , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Shuah Khan , Suren Baghdasaryan , Vlastimil Babka , damon@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 0/7] mm/damon/reclaim,lru_sort: monitor all system rams by default Date: Wed, 29 Apr 2026 07:30:52 -0700 Message-ID: <20260429143053.93890-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260429041232.90257-1-sj@kernel.org> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 44867120017 X-Stat-Signature: dnf6jii4x4kyrejs13z5bt53hn97nrkb X-HE-Tag: 1777473058-779499 X-HE-Meta: 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 fLXBJqsA 0Z/ySS0JIBHOuGYZcMBgUq3/ekNu9m3FwRIafOZ11Csrto3+rlQydHtUQBhuv1V4dHTbFTGRJhXoDF4Is64UOtUeF3wmnF0V65TXmXLYAlOcndtyU7CnOvpXCf1tY4S1PF7Qs1MBXIg2XfrPcjBwOdNxYNmcSkKtss3ES36KIXyIDJFV3z577MsuDy5Gkz808IbZJcEzouapq5pOFxYkj2f++u1CbLFKF6/w/bmxFswxXpueQ3lv9uSiUD/RBAruQ9oEyiQVVlC2TB0UEPGBAmSY1gg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 28 Apr 2026 21:12:22 -0700 SeongJae Park wrote: > DAMON_RECLAIM and DAMON_LRU_SORT set the biggest 'System RAM' resource > of the system as the default monitoring target address range. The main > intention behind the design is to minimize the overhead coming from > monitoring of non-System RAM areas. > > This could result in an odd setup when there are multiple discrete > System RAMs of considerable sizes. For example, there are System RAMs > each having 500 GiB size. In this case, only the first 500 GiB will be > set as the monitoring region by default. This is particularly common on > NUMA systems. Hence the modules allow users to set the monitoring > target address range using the module parameters if the default setup > doesn't work for them. In other words, the current design trades ease > of setup for lower overhead. > > However, because DAMON utilizes the sampling based access check and the > adaptive regions adjustment mechanisms, the overhead from the monitoring > of non-System RAM areas should be negligible in most setups. Meanwhile, > the setup complexity is causing real headaches for users who need to run > those modules on various types of systems. That is, the current > tradeoff is not a good deal. > > Set the physical address range that can cover all System RAM areas of > the system as the default monitoring regions for DAMON_RECLAIM and > DAMON_LRU_SORT. FYI, Sashiko reviews and my review of the reviews are available on replies to this thread that Cc-ing only me and damon@lists.linux.dev (https://lore.kernel.org/20260429041232.90257-1-sj@kernel.org). In short, no real issue that blocks this series is found by Sashiko. Thanks, SJ [...]