[RFC PATCH v3 25/37] Docs/admin-guide/mm/damon/usage: document sample filters dir

SeongJae Park
2025-12-08T06:30:28Z

Update DAMON usage document for the added DAMON sysfs files for
installing and setting the access sample results filtering.

Signed-off-by: SeongJae Park <sj@kernel.org>
---
Documentation/admin-guide/mm/damon/usage.rst | 25 +++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index 897a89950351..365a4548a5ba 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -66,6 +66,8 @@ comma (",").
│ │ │ │ │ │ intervals/sample_us,aggr_us,update_us
│ │ │ │ │ │ │ intervals_goal/access_bp,aggrs,min_sample_us,max_sample_us
│ │ │ │ │ │ sample/primitives/page_table,page_faults
+ │ │ │ │ │ │ sample/filters/nr_filters
+ │ │ │ │ │ │ │ 0/type,matching,allow,cpumask
│ │ │ │ │ │ nr_regions/min,max
│ │ │ │ │ :ref:`targets <sysfs_targets>`/nr_targets
│ │ │ │ │ │ :ref:`0 <sysfs_target>`/pid_target,obsolete_target
@@ -233,7 +235,8 @@ writing to and rading from the files.
For more details about the intervals and monitoring regions range, please refer
to the Design document (:doc:`/mm/damon/design`).

-Under ``sample`` directory, a directory, ``primitives`` exists.
+Under ``sample`` directory, two directories, ``primitives`` and ``filters``
+exist.

contexts/<N>/monitoring_attrs/sample/primitives/
------------------------------------------------
@@ -245,6 +248,26 @@ to these files, users can select whether to use the :ref:`page table accessed
bit <damon_design_pte_accessed_bit_access_check>` and :ref:`page fault events
<damon_design_page_fault_access_check>`, respectively.

+contexts/<N>/monitoring_attrs/sample/filters/
+---------------------------------------------
+
+This directory is for control of the :ref:`access sampling results filters
+<damon_design_sampling_results_filters>`. At the beginning, this directory has
+only one file, ``nr_filters``. Writing a positive integer ``<n>`` to the file
+generates directories of the number, named ``0`` to ``<n - 1>``. The generated
+directories represent the sampling result filters to install to the DAMON
+context, in the order of the directory names. Writing ``0`` to ``nr_filters``
+removes the directories.
+
+Under the individual filter directory, five files, ``type``, ``matching``,
+``allow``, and ``cpumask`` exist. The first three files are same to the
+properties of the filter specified on the :ref:`design doc
+<damon_design_sampling_results_filters>`.
+
+Users can specify the cpumask of the filter by writing it to ``cpumask``. The
+format for ``cpumask`` input is same to that for other cpumask inputs like that
+for cgroup cpusets.
+
.. _damon_usage_sysfs_monitoring_intervals_goal:

contexts/<N>/monitoring_attrs/intervals/intervals_goal/
--
2.47.3