Document DAMON sampling and aggregation intervals auto-tuning design.
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
Documentation/mm/damon/design.rst | 34 +++++++++++++++++++++++++++++++
1 file changed, 34 insertions(+)
diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index e28c6a1b40ae..c8e906ac3965 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -313,6 +313,10 @@ sufficient for the given purpose, it shouldn't be unnecessarily further
lowered. It is recommended to be set proportional to ``aggregation interval``.
By default, the ratio is set as ``1/20``, and it is still recommended.
+Based on the manual tuning guide, DAMON provides more intuitive knob-based
+intervals auto tuning mechanism. Please refer to :ref:`the design document of
+the feature <damon_design_monitoring_intervals_autotuning>` for detail.
+
Refer to below documents for an example tuning based on the above guide.
.. toctree::
@@ -321,6 +325,36 @@ Refer to below documents for an example tuning based on the above guide.
monitoring_intervals_tuning_example
+.. _damon_design_monitoring_intervals_autotuning:
+
+Monitoring Intervals Auto-tuning
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+DAMON provides automatic tuning of the ``sampling interval`` and ``aggregation
+interval`` based on the :ref:`the tuning guide idea
+<damon_design_monitoring_params_tuning_guide>`. The tuning mechanism allows
+users to set the aimed amount of heats to observe with DAMON within given time
+interval. The target can be specified by the user as a ratio of access check
+samples that gave positive result to the total samples (``samples_bp``) that
+measured within a given number of aggregations (``aggrs``). The mechanism
+calculates the ratio of access check samples for ``aggrs`` aggregations, and
+increases or decrease the ``sampleing interval`` and ``aggregation interval``
+in same ratio, if the samples ratio is lower or higher than the target,
+respectively. The ratio of the intervals change is decided in proportion to
+the distance between current samples ratio and the target ratio.
+
+The user can further set the minimum and maximum ``sampling interval`` that can
+be set by the tuning mechanism using two parameters (``min_sample_us`` and
+``max_sample_us``). Because the tuning mechanism changes ``sampling interval``
+and ``aggregation interval`` in same ratio always, the minimum and maximum
+``aggregation interval`` after each of the tuning changes can automatically set
+together.
+
+The tuning is turned off by default, and need to be set explicitly by the user.
+As a rule of thumbs and the Parreto principle, 20% access samples ratio target
+is recommended.
+
+
.. _damon_design_damos:
Operation Schemes
--
2.39.5
