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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 05/11] Docs/mm/damon/design: document fail_charge_{num,denom} Date: Fri, 10 Apr 2026 07:20:26 -0700 Message-ID: <20260410142034.83798-6-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260410142034.83798-1-sj@kernel.org> References: <20260410142034.83798-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 69C66120006 X-Stat-Signature: ceyynuc83oh48dgsmehm1igai6tpq58d X-Rspam-User: X-HE-Tag: 1775830847-724618 X-HE-Meta: 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 mSSNGmIM K/uwP 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