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authorSeongJae Park <sj@kernel.org>2025-10-26 11:22:09 -0700
committerAndrew Morton <akpm@linux-foundation.org>2025-11-16 17:28:21 -0800
commit29221406f09d8c4b523ffea86c5c69f628c2f6db (patch)
tree5fd3101c6f0a875f6725bec9331f45e26ed816b2 /Documentation/admin-guide
parenta01386c16dc2d4ef3284c415cfe414f8137e0ea1 (diff)
Docs/admin-guide/mm/damon/usage: document empty target regions commit behavior
Committing a monitoring target with empty target regions is for keeping the current monitoring results. This behavior was introduced by commit 973233600676 ("mm/damon/sysfs: update monitoring target regions for online input commit"). The behavior is not documented, though. Update the usage document for clarifying this behavior. Link: https://lkml.kernel.org/r/20251026182216.118200-5-sj@kernel.org Signed-off-by: SeongJae Park <sj@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'Documentation/admin-guide')
-rw-r--r--Documentation/admin-guide/mm/damon/usage.rst8
1 files changed, 7 insertions, 1 deletions
diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst
index 98958975604d..c630f2662695 100644
--- a/Documentation/admin-guide/mm/damon/usage.rst
+++ b/Documentation/admin-guide/mm/damon/usage.rst
@@ -134,7 +134,8 @@ Users can write below commands for the kdamond to the ``state`` file.
- ``on``: Start running.
- ``off``: Stop running.
- ``commit``: Read the user inputs in the sysfs files except ``state`` file
- again.
+ again. Monitoring :ref:`target region <sysfs_regions>` inputs are also be
+ ignored if no target region is specified.
- ``update_tuned_intervals``: Update the contents of ``sample_us`` and
``aggr_us`` files of the kdamond with the auto-tuning applied ``sampling
interval`` and ``aggregation interval`` for the files. Please refer to
@@ -289,6 +290,11 @@ In the beginning, this directory has only one file, ``nr_regions``. Writing a
number (``N``) to the file creates the number of child directories named ``0``
to ``N-1``. Each directory represents each initial monitoring target region.
+If ``nr_regions`` is zero when committing new DAMON parameters online (writing
+``commit`` to ``state`` file of :ref:`kdamond <sysfs_kdamond>`), the commit
+logic ignores the target regions. In other words, the current monitoring
+results for the target are preserved.
+
.. _sysfs_region:
regions/<N>/