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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 v5.1 05/11] Docs/mm/damon/design: document fail_charge_{num,denom} Date: Sat, 11 Apr 2026 09:48:58 -0700 Message-ID: <20260411164908.77189-6-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260411164908.77189-1-sj@kernel.org> References: <20260411164908.77189-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 1D1C6A000F X-Stat-Signature: ikysnu1srotfnwjezjcimzf3bnc67pwb X-HE-Tag: 1775926169-714386 X-HE-Meta: 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 9jUUZdTC /+ps9OqMHc+cj/Fgww0803A/hkATZ6tZBrwj8P7OoT8glmVkEJyQuyni8GKjj2NneCT5aW2j6w0bbAGBRb+YpBouW0DOQSZbkUfdEpaEhByYBl7GyeXG3U9lMwbk31HpnaSZtVvNyGU2ovtcWczkbZskJ/ws3ByvvIovkTziAPnBO6Xc2wt0Vq+z1a+wbKVfE9zpGMzZlrbZP6leOhuq342e4PQCouefkkUUBCASqNyvOlG17hvGx//5lytS1BtTesJym4+Zaezz0lcyrM5y8AI0TxBTIq0oGEm9b 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