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Docs/admin-guide/mm/damon/usage: document DAMOS filter 'allow' sysfs file

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Update DAMON usage document for the newly added 'allow' sysfs file for
DAMOS filters.

Link: https://lkml.kernel.org/r/20250109175126.57878-11-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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SeongJae Park 2025-01-09 09:51:26 -08:00 committed by Andrew Morton
parent e8fef78ca8
commit 627a2a2429
1 changed files with 19 additions and 14 deletions
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33
Documentation/admin-guide/mm/damon/usage.rst
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@ -83,7 +83,7 @@ comma (",").
│ │ │ │ │ │ │ │ │ 0/target_metric,target_value,current_value
│ │ │ │ │ │ │ :ref:`watermarks <sysfs_watermarks>`/metric,interval_us,high,mid,low
│ │ │ │ │ │ │ :ref:`filters <sysfs_filters>`/nr_filters
│ │ │ │ │ │ │ │ 0/type,matching,memcg_id
│ │ │ │ │ │ │ │ 0/type,matching,memcg_id,allow
│ │ │ │ │ │ │ :ref:`stats <sysfs_schemes_stats>`/nr_tried,sz_tried,nr_applied,sz_applied,sz_ops_filter_passed,qt_exceeds
│ │ │ │ │ │ │ :ref:`tried_regions <sysfs_schemes_tried_regions>`/total_bytes
│ │ │ │ │ │ │ │ 0/start,end,nr_accesses,age,sz_filter_passed
@ -406,13 +406,14 @@ number (``N``) to the file creates the number of child directories named ``0``
to ``N-1``. Each directory represents each filter. The filters are evaluated
in the numeric order.
Each filter directory contains six files, namely ``type``, ``matcing``,
``memcg_path``, ``addr_start``, ``addr_end``, and ``target_idx``. To ``type``
file, you can write one of five special keywords: ``anon`` for anonymous pages,
``memcg`` for specific memory cgroup, ``young`` for young pages, ``addr`` for
specific address range (an open-ended interval), or ``target`` for specific
DAMON monitoring target filtering. Meaning of the types are same to the
description on the :ref:`design doc <damon_design_damos_filters>`.
Each filter directory contains seven files, namely ``type``, ``matching``,
``allow``, ``memcg_path``, ``addr_start``, ``addr_end``, and ``target_idx``.
To ``type`` file, you can write one of five special keywords: ``anon`` for
anonymous pages, ``memcg`` for specific memory cgroup, ``young`` for young
pages, ``addr`` for specific address range (an open-ended interval), or
``target`` for specific DAMON monitoring target filtering. Meaning of the
types are same to the description on the :ref:`design doc
<damon_design_damos_filters>`.
In case of the memory cgroup filtering, you can specify the memory cgroup of
the interest by writing the path of the memory cgroup from the cgroups mount
@ -422,25 +423,29 @@ specify the start and end address of the range to ``addr_start`` and
you can specify the index of the target between the list of the DAMON context's
monitoring targets list to ``target_idx`` file.
You can write ``Y`` or ``N`` to ``matching`` file to filter out pages that does
or does not match to the type, respectively. Then, the scheme's action will
not be applied to the pages that specified to be filtered out.
You can write ``Y`` or ``N`` to ``matching`` file to specify whether the filter
is for memory that matches the ``type``. You can write ``Y`` or ``N`` to
``allow`` file to specify if applying the action to the memory that satisfies
the ``type`` and ``matching`` should be allowed or not.
For example, below restricts a DAMOS action to be applied to only non-anonymous
pages of all memory cgroups except ``/having_care_already``.::
# echo 2 > nr_filters
# # filter out anonymous pages
# # disallow anonymous pages
echo anon > 0/type
echo Y > 0/matching
echo N > 0/allow
# # further filter out all cgroups except one at '/having_care_already'
echo memcg > 1/type
echo /having_care_already > 1/memcg_path
echo Y > 1/matching
echo N > 1/allow
Refer to the :ref:`DAMOS filters design documentation
<damon_design_damos_filters>` for more details including when each of the
filters are supported and differences on stats.
<damon_design_damos_filters>` for more details including how multiple filters
of different ``allow`` works, when each of the filters are supported, and
differences on stats.
.. _sysfs_schemes_stats: