linux-kernel - [RFC PATCH 17/18] Docs/admin-guide/mm/damon/usage: document schemes/<s>/tried

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Date:   Wed, 19 Oct 2022 00:13:16 +0000
From:   SeongJae Park <sj@...nel.org>
To:     SeongJae Park <sj@...nel.org>, Jonathan Corbet <corbet@....net>
Cc:     damon@...ts.linux.dev, linux-mm@...ck.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [RFC PATCH 17/18] Docs/admin-guide/mm/damon/usage: document schemes/<s>/tried_regions directory

Document 'tried_regions' directory in DAMON sysfs interface usage in the
administrator guide.

Signed-off-by: SeongJae Park <sj@...nel.org>
---
 Documentation/admin-guide/mm/damon/usage.rst | 44 ++++++++++++++++++--
 1 file changed, 41 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index b47b0cbbd491..649d63ecf67f 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -88,6 +88,9 @@ comma (","). ::
     │ │ │ │ │ │ │ │ weights/sz_permil,nr_accesses_permil,age_permil
     │ │ │ │ │ │ │ watermarks/metric,interval_us,high,mid,low
     │ │ │ │ │ │ │ stats/nr_tried,sz_tried,nr_applied,sz_applied,qt_exceeds
+    │ │ │ │ │ │ │ tried_regions/
+    │ │ │ │ │ │ │ │ 0/start,end,nr_accesses,age
+    │ │ │ │ │ │ │ │ ...
     │ │ │ │ │ │ ...
     │ │ │ │ ...
     │ │ ...
@@ -125,7 +128,14 @@ in the state.  Writing ``commit`` to the ``state`` file makes kdamond reads the
 user inputs in the sysfs files except ``state`` file again.  Writing
 ``update_schemes_stats`` to ``state`` file updates the contents of stats files
 for each DAMON-based operation scheme of the kdamond.  For details of the
-stats, please refer to :ref:`stats section <sysfs_schemes_stats>`.
+stats, please refer to :ref:`stats section <sysfs_schemes_stats>`.  Writing
+``update_schemes_regions`` to ``state`` file updates the DAMON-based operation
+scheme action tried regions directory for each DAMON-based operation scheme of
+the kdamond.  Writing ``clear_schemes_regions`` to ``state`` file clears the
+DAMON-based operating scheme action tried regions directory for each
+DAMON-based operation scheme of the kdamond.  For details of the DAMON-based
+operation scheme action tried regions directory, please refer to
+:ref:tried_regions section <sysfs_schemes_tried_regions>`.
 
 If the state is ``on``, reading ``pid`` shows the pid of the kdamond thread.
 
@@ -166,6 +176,8 @@ You can set and get what type of monitoring operations DAMON will use for the
 context by writing one of the keywords listed in ``avail_operations`` file and
 reading from the ``operations`` file.
 
+.. _sysfs_monitoring_attrs:
+
 contexts/<N>/monitoring_attrs/
 ------------------------------
 
@@ -252,8 +264,9 @@ to ``N-1``.  Each directory represents each DAMON-based operation scheme.
 schemes/<N>/
 ------------
 
-In each scheme directory, four directories (``access_pattern``, ``quotas``,
-``watermarks``, and ``stats``) and one file (``action``) exist.
+In each scheme directory, five directories (``access_pattern``, ``quotas``,
+``watermarks``, ``stats``, and ``tried_regions``) and one file (``action``)
+exist.
 
 The ``action`` file is for setting and getting what action you want to apply to
 memory regions having specific access pattern of the interest.  The keywords
@@ -348,6 +361,31 @@ should ask DAMON sysfs interface to updte the content of the files for the
 stats by writing a special keyword, ``update_schemes_stats`` to the relevant
 ``kdamonds/<N>/state`` file.
 
+.. _sysfs_schemes_tried_regions:
+
+schemes/<N>/tried_regions/
+--------------------------
+
+When a special keyword, ``update_schemes_regions``, is written to the relevant
+``kdamonds/<N>/state`` file, DAMON creates directories named integer starting
+from ``0`` under this directory.  Each directory contains files exposing
+detailed information about each of the memory region that the corresponding
+scheme's ``action`` has tried to be applied under this directory, during next
+:ref:`aggregation interval <sysfs_monitoring_attrs>`.  The information includes
+address range, ``nr_accesses``, , and ``age`` of the region.
+
+The directories will be removed when another special keyword,
+``clear_schemes_regions``, is written to the relevant ``kdamonds/<N>/state``
+file.
+
+tried_regions/<N>/
+------------------
+
+In each region directory, you will find four files (``start``, ``end``,
+``nr_accesses``, and ``age``).  Reading the files will show the start and end
+addresses, ``nr_accesses``, and ``age`` of the region that corresponding
+DAMON-based operation scheme ``action`` has tried to be applied.
+
 Example
 ~~~~~~~
 
-- 
2.25.1