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Docs/mm/damon/design: document node_mem_{used,free}_bp

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Add description of DAMOS quota goal metrics for NUMA node utilization on
the DAMON deesign document.

Link: https://lkml.kernel.org/r/20250420194030.75838-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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SeongJae Park 2025-04-20 12:40:27 -07:00 committed by Andrew Morton
parent 85fcf0ffc4
commit b3b95a3594
1 changed files with 9 additions and 4 deletions
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13
Documentation/mm/damon/design.rst
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@ -550,10 +550,10 @@ aggressiveness (the quota) of the corresponding scheme. For example, if DAMOS
is under achieving the goal, DAMOS automatically increases the quota. If DAMOS
is over achieving the goal, it decreases the quota.
The goal can be specified with three parameters, namely ``target_metric``,
``target_value``, and ``current_value``. The auto-tuning mechanism tries to
make ``current_value`` of ``target_metric`` be same to ``target_value``.
Currently, two ``target_metric`` are provided.
The goal can be specified with four parameters, namely ``target_metric``,
``target_value``, ``current_value`` and ``nid``. The auto-tuning mechanism
tries to make ``current_value`` of ``target_metric`` be same to
``target_value``.
- ``user_input``: User-provided value. Users could use any metric that they
has interest in for the value. Use space main workload's latency or
@ -565,6 +565,11 @@ Currently, two ``target_metric`` are provided.
in microseconds that measured from last quota reset to next quota reset.
DAMOS does the measurement on its own, so only ``target_value`` need to be
set by users at the initial time. In other words, DAMOS does self-feedback.
- ``node_mem_used_bp``: Specific NUMA node's used memory ratio in bp (1/10,000).
- ``node_mem_free_bp``: Specific NUMA node's free memory ratio in bp (1/10,000).
``nid`` is optionally required for only ``node_mem_used_bp`` and
``node_mem_free_bp`` to point the specific NUMA node.
To know how user-space can set the tuning goal metric, the target value, and/or
the current value via :ref:`DAMON sysfs interface <sysfs_interface>`, refer to