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Howlett" , Andrew Morton , 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: [RFC PATCH v5.2 05/11] Docs/mm/damon/design: document fail_charge_{num,denom} Date: Sun, 12 Apr 2026 09:19:48 -0700 Message-ID: <20260412161957.82835-6-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260412161957.82835-1-sj@kernel.org> References: <20260412161957.82835-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: zeooptjyzukm3nbu44t1wkh54pb9qebb X-Rspamd-Queue-Id: 4227B18000D X-Rspamd-Server: rspam09 X-HE-Tag: 1776010805-716552 X-HE-Meta: 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 FeW5651s Oi7ssK4e88KFg5Gakpz8s4jM8e5RhtILLnhZ7P7IZJTS81ltM3MKUnmqD/JxkfOYMErhXNPl5TIYib9AEgOVrAK44l9qeQTO8WfXLpnxW+oSgBV66NeNKMz5iLRxjxONpE5K/VGe91LkqLjy4TODmouwPkdswLyH9VhDlgxSffcz8Dq+jqz4jHmzFg1ioLZ6iePqfAIotLmV8WDLJdmNRHY91obZH1sJbXvv15Cwa2wqzkWxoAprDMZaNCWdAEALFYOZyS25LjtOYcBVz6JxWApVr9BZQZdsjc8Yu 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 DAMOS action failed region quota charge ratio. Signed-off-by: SeongJae Park --- Documentation/mm/damon/design.rst | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst index 622d24e35961e..fa7392b5a331d 100644 --- a/Documentation/mm/damon/design.rst +++ b/Documentation/mm/damon/design.rst @@ -576,6 +576,28 @@ interface `, refer to :ref:`weights ` part of the documentation. +.. _damon_design_damos_quotas_failed_memory_charging_ratio: + +Action-failed Memory Charging Ratio +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +DAMOS action to a given region can fail for some subsets of the memory of the +region. For example, if the action is ``pageout`` and the region has some +unreclaimable pages, applying the action to the pages will fail. The amount of +system resource that is taken for such failed action applications is usually +different from that for successful action applications. For such cases, users +can set different charging ratio for such failed memory. The ratio can be +specified using ``fail_charge_num`` and ``fail_charge_denom`` parameters. The +two parameters represent the numerator and denominator of the ratio. The +feature is enabled only if ``fail_charge_denom`` is not zero. + +For example, let's suppose a DAMOS action is applied to a region of 1,000 MiB +size. The action is successfully applied to only 700 MiB of the region. +``fail_charge_num`` and ``fail_charge_denom`` are set to ``1`` and ``1024``, +respectively. Then only 700 MiB and 300 KiB of size (``700 MiB + 300 MiB * 1 / +1024``) will be charged. + + .. _damon_design_damos_quotas_auto_tuning: Aim-oriented Feedback-driven Auto-tuning -- 2.47.3