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Howlett" , 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: [PATCH 05/11] Docs/mm/damon/design: document fail_charge_{num,denom} Date: Mon, 27 Apr 2026 18:33:54 -0700 Message-ID: <20260428013402.115171-6-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260428013402.115171-1-sj@kernel.org> References: <20260428013402.115171-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 815B0C000E X-Stat-Signature: dasu5rx4o9w5tgo84usj3446euuk481e X-HE-Tag: 1777340072-876998 X-HE-Meta: U2FsdGVkX19bnaxoRvqhwg0DqcNXhaIA3mFnJZu/gtIBbKnV5TmyARv9wRH4EwzJQB+NkP8KrFDmVq6Ipfzr0MbEFty5ore8O2du9orxG42PXHDpbJ06WVQXitIl2Y8vWQyLAoVrQIbXu29kq0FaS7Pu/r7m5zfoEwAmKrlVr5S9QRof+KNJZodTNnk/8SuwLVTJe1wveqrXjP3qBgLPXzxn0iV/13/VaOQYTsWRchu2MhOUOQOThdCf2E5b/xpaTZscOwXRCZtmg69vSipKyZKhQ5tlaAnuS1GxLixW+tJFDYOzq+p8GRqK1dtTVR2TKBQtz7Yrj6fNjtT5ZxQzeMKOqHIJTfcrPARhX95/afWop5tyG+z1/54XPi2CZBW1Zt7g35p8RiokESiwtjYFSIvbcFg09+gMtPqiTSpLoLKvHq7EqKtryip8Vk7RQR840R4Br02ZJJoM0I1mussVu7esznXBuB9SWv1KS9DqEsJNk8wXmN3f7PhLvycjrOhb/mkFd2BNUkFnpNGBlltQG3NqaPLjL3ZzhlOURn00CW/+fpQlx1xxKu+QleaavZvUJElaU2FKHi8Sb3pdBKUd+J+YXkcWqB9HpPgLJtFrMkKvHDu3A9EXN38vqAvtMPaZ4NqkGJ1MB86ry56b9Urxb6u9j4eLhM8BgvP4ELVKgoC/wl6UbP5pZX9UuakVNy3KrbE9IUjy/AldfhR4s5qxIYKJzwAhh56CJksxBcoIz4NwahRceQOAIrYRomUrXkgKywxx93g2SW/l4W3qD2ghBQTeGo5lRNJFWDKGYxMofX3ehe4R6g3a9YXB/fvAdSGWWdcZeIKbJwW5T2YaK6YQRSBv9MK8KHC9OmOtD45Qnopk/d1H8bstZXRjT3xQk7Ifg9PH0oPhvms5yVqH2k1DvMTVmIl6pVh5uLZLSRSuJD3fFGgMQUiZZyEdjeyMBS7A9TxE4QgZcS/ntJYMoKn c+STYH8V fr7pSDg49FAkoXMGXpHWSWvmw1YNDDsSFar0ZfhiWmT2yWhfxdaednVBOAv7j/wp8AbEzkuMMQUb5plqTct0f440MpDq1rxyhyBZ1O61mYsemZSZmYmV9+UqQzPssn2BAQ/obtZEC79510rdYpXRK1h+9ugDyKwTqrkU4+EwQtMFxWjvyn7oPsDc/dZ0hlls/mW0kOPUVSLHHHfnPR8PDbDStT/E6zCMBeZEdK286P3AgbcRhAW9x4wgsxEwr4YxK0fg3mu6iYqZo+Gu+YLRfll6dlBhE8bP+dIRn 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