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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 v2 3/9] Docs/mm/damon/design: document fail_charge_{num,denom} Date: Sun, 5 Apr 2026 08:12:21 -0700 Message-ID: <20260405151232.102690-4-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260405151232.102690-1-sj@kernel.org> References: <20260405151232.102690-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: f5sxk36d3gzihaxkbuyk8b6u3txt5s47 X-Rspamd-Queue-Id: 046DCC000A X-Rspamd-Server: rspam09 X-HE-Tag: 1775401958-982474 X-HE-Meta: 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 fqzM8J4k A2duFExf1PQwxJFcfegB78kLUJK1iYA7mNHxRLKCksOiLWkNZiUvnFrefjuBTsJhZ7zPlBhl2C7SiJ27wKvOa2VAS4Qg3t4rQu1YxRkoyJDKy+Ld26p+icoEqb3St2dMx3oT2RvpisyDQVAUPiwYjPOwhYgJZn2qi8P1IF8rQLf3uj0p6ZWHfmvdicYU0dxjQyUEm7kq0M7ZSQcmmX6E1Mpncd2HZK8P3IYX40UXl+NLgFdWHlfioL7TsigNr2bZrnbkLRx4DHk+ZRZjWTYuGUpd2+A== 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 | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst index 510ec6375178d..3ea9c81b756c8 100644 --- a/Documentation/mm/damon/design.rst +++ b/Documentation/mm/damon/design.rst @@ -572,6 +572,27 @@ 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. + +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