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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 v3 04/10] Docs/mm/damon/design: document fail_charge_{num,denom} Date: Mon, 6 Apr 2026 18:05:26 -0700 Message-ID: <20260407010536.83603-5-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260407010536.83603-1-sj@kernel.org> References: <20260407010536.83603-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 4F9DF140012 X-Stat-Signature: jih9jm7rtgiygi16mxe15duoiksqxxan X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1775523942-470469 X-HE-Meta: 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 TgCpzTtf 4BULrIilJYjyJ4AdY16XoGe6xJe8AATvSgZq9oK1EQb38XLbQRnxxeokCcFX26WFokfMQ6xUP2jM3cChYzADsri73C9xKodquopP15/6icuULi1vvss9bt22qEgzbflZmFGHnz8NytbT0eGM8bg6xLy106fIZJ5RFjANeKr34Eg/07Nuss61JwDijguASd+DMaR6husrtNjTBBhhnoADXYSuvZ0MrmSMdW4doyKwBeuHTDsi1EGVLS80i3d/tMeH5USIEz6oh/EjlS2ypvZQ6H2aJLg== 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 510ec6375178d..94e898b671d15 100644 --- a/Documentation/mm/damon/design.rst +++ b/Documentation/mm/damon/design.rst @@ -572,6 +572,28 @@ 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