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Howlett" , Andrew Morton , David Hildenbrand , Jonathan Corbet , Lorenzo Stoakes , Michal Hocko , Mike Rapoport , Suren Baghdasaryan , Vlastimil Babka , damon@lists.linux.dev, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH 09/12] Docs/mm/damon/design: update for max_nr_snapshots Date: Sun, 23 Nov 2025 10:43:23 -0800 Message-ID: <20251123184329.85287-10-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20251123184329.85287-1-sj@kernel.org> References: <20251123184329.85287-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 215F31C0007 X-Stat-Signature: zw9zi9o6qrdacpnajgo46sbgzqfgp51r X-Rspam-User: X-HE-Tag: 1763923427-747950 X-HE-Meta: U2FsdGVkX1/SNDv3LWxgQ9+XzQqK595192s6ES0sLKjmr/LoQQmSJP2IkiJQHOQUzvOkc3Q23HdNlOnJo4oefsz3KzOICz3utzVT44aDdMNO9N/6sqvXKuc08NCFgDgwn2tpH4rkh7KAjNvmZArjRYiWXyyZnTOxiQaMVgG8RMSHwN4hJo/j6zZqoCClZ2/M3QGAriIeey5fOOT1GeH8+dCqAl46zWbLMAGQk0KrZ7PH0y7AX0RaF/3UGR1ofJ8UyPPCk0VwjP/sT1WByzc92pYwmrsauZnFK5iRmBqhVyE/rixa1nHfo3/S6euA02irhpHZdPkhQ4LIIYO6g35v5O2BnoTr9OXc9ZCJEgiZlwQotOOBsnSvvxoN4S9VVU/tjtuhzeQ1UASURtgSc6fEQgNMAFZrLmneH/6mfBY17SsK/yMr92pATGCsd/iWLBP84GAtzG/WiF/RfOqdOhzQceKuq6x0VYw43rhZ0VJr2MH8Y4sfxGtA0ZkRIGaO+PrvyZUK+iP/vRUYcRSCq2xCGNVSAIeit1/gR0Mev2lodL+mnDpK5rNbyQ+WFzm8lcPqUO4PgwKuGeLZrr7p9atmksOitaY+J2B+o3wBUI4y7obgmINe0uUyNbNpgZREq2mr3KxpnJZIZcg1mmjDLnLpH/wX71gQmBRyEsGMeLSvjvr/S4JmFDosQN8UZ3NCH0CwmsChuDjWhuTMhNfb0jaHpRameuSETLW8KPTb+76+PbDOO5UPgzbbPkBrChKTa1WBUhYpEGXHvFLexpNtaJQggCm8CYNVziBh4btl+3K8x7Ka7BaHAjcSjXaPoVPNCYvo80g/yoLCaZLwmpBgJqEuru9bib6jZirHJ2fahggPE4Nftsbkyk7T7QlEL74yfYZ7wWooM/xJ/Ieg/6FhKxS3J9N8D+mVbwMiNaMkQ3It/62Sg70pS8LiKoWknyHemQMTFlEkwasSH1N4DOjobo7 7P1C+nyS IJoJJ6Cco2hprpZOR4N5PLCrfkdkphKlLibEAmtj/OD8lZVJV9RjSCV6Cc4HfNNWKa/FUwnwxnGP/5/Hs5wqfC1S3vpOV9FdDa4xY2wvEfNWx4DGrNVLU7pvJj7nKEq1nUmTZxCSJ2bB/AYPn3KCwFIB+46wtSBZZgnS0yV0996A5UC7qL6Dj+crlzGxYSKJzssmWy5QzF/hIcf6B4Dk0vF+cRJqwZFbs7VjSqYqRon3GAXMu0jIsKgk+SZHug3usR0h83Yi+fjpDp0bSX37zaxKH5w== 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: Update DAMON design document for the newly added snapshot level DAMOS deactivation feature, max_nr_snapshots. Signed-off-by: SeongJae Park --- Documentation/mm/damon/design.rst | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst index 5cc7b7d662be..7fd819b8bbf7 100644 --- a/Documentation/mm/damon/design.rst +++ b/Documentation/mm/damon/design.rst @@ -720,6 +720,7 @@ scheme's execution. - ``qt_exceeds``: Total number of times the quota of the scheme has exceeded. - ``nr_snapshots``: Total number of DAMON snapshots that the scheme is tried to be applied. +- ``max_nr_snapshots``: Upper limit of ``nr_snapshots``. "A scheme is tried to be applied to a region" means DAMOS core logic determined the region is eligible to apply the scheme's :ref:`action @@ -741,6 +742,10 @@ to exclude anonymous pages and the region has only anonymous pages, or if the action is ``pageout`` while all pages of the region are unreclaimable, applying the action to the region will fail. +Unlike normal stats, ``max_nr_snapshots`` is set by users. If it is set as +non-zero and ``nr_snapshots`` be same to or greater than ``nr_snapshots``, the +scheme is deactivated. + To know how user-space can read the stats via :ref:`DAMON sysfs interface `, refer to :ref:s`stats ` part of the documentation. -- 2.47.3