Docs/admin-guide/mm/damon/stat: document aggr_interval_us parameter

Commit cc7ceb1d14b0 ("mm/damon/stat: expose the current tuned aggregation
interval"), has introduced 'aggr_interval_us' parameter for DAMON_STAT.
But the new parameter is not yet documented.  Document it on the usage
document for the module.

Link: https://lkml.kernel.org/r/20251026182216.118200-8-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>

diff --git a/Documentation/admin-guide/mm/damon/stat.rst b/Documentation/admin-guide/mm/damon/stat.rst
index 20f540a9d3d299e034964984dc43c26c17a37cf5..754f98d47617a462f54744311200611666d625b0 100644 (file)
--- a/Documentation/admin-guide/mm/damon/stat.rst
+++ b/Documentation/admin-guide/mm/damon/stat.rst
@@ -10,6 +10,8 @@ on the system's entire physical memory using DAMON, and provides simplified
 access monitoring results statistics, namely idle time percentiles and
 estimated memory bandwidth.
 
+.. _damon_stat_monitoring_accuracy_overhead:
+
 Monitoring Accuracy and Overhead
 ================================
 
@@ -19,7 +21,9 @@ overhead minimum.  It auto-tunes the intervals aiming 4 % of observable access
 events to be captured in each snapshot, while limiting the resulting sampling
 interval to be 5 milliseconds in minimum and 10 seconds in maximum.  On a few
 production server systems, it resulted in consuming only 0.x % single CPU time,
-while capturing reasonable quality of access patterns.
+while capturing reasonable quality of access patterns.  The tuning-resulting
+intervals can be retrieved via ``aggr_interval_us`` :ref:`parameter
+<damon_stat_aggr_interval_us>`.
 
 Interface: Module Parameters
 ============================
@@ -41,6 +45,18 @@ You can enable DAMON_STAT by setting the value of this parameter as ``Y``.
 Setting it as ``N`` disables DAMON_STAT.  The default value is set by
 ``CONFIG_DAMON_STAT_ENABLED_DEFAULT`` build config option.
 
+.. _damon_stat_aggr_interval_us:
+
+aggr_interval_us
+----------------
+
+Auto-tuned aggregation time interval in microseconds.
+
+Users can read the aggregation interval of DAMON that is being used by the
+DAMON instance for DAMON_STAT.  It is :ref:`auto-tuned
+<damon_stat_monitoring_accuracy_overhead>` and therefore the value is
+dynamically changed.
+
 estimated_memory_bandwidth
 --------------------------