The patch titled
Subject: Docs/admin-guide/mm/damon: document DAMON-based Operation Schemes
has been added to the -mm tree. Its filename is
docs-admin-guide-mm-damon-document-damon-based-operation-schemes.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/docs-admin-guide-mm-damon-document-damon-based-operation-schemes.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/docs-admin-guide-mm-damon-document-damon-based-operation-schemes.patch
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------------------------------------------------------
From: SeongJae Park <sj@xxxxxxxxxx>
Subject: Docs/admin-guide/mm/damon: document DAMON-based Operation Schemes
This commit add description of DAMON-based operation schemes in the DAMON
documents.
Link: https://lkml.kernel.org/r/20211001125604.29660-8-sj@xxxxxxxxxx
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Cc: Amit Shah <amit@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: David Rienjes <rientjes@xxxxxxxxxx>
Cc: David Woodhouse <dwmw@xxxxxxxxxx>
Cc: Greg Thelen <gthelen@xxxxxxxxxx>
Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Leonard Foerster <foersleo@xxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Markus Boehme <markubo@xxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Shuah Khan <shuah@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/mm/damon/start.rst | 11 +++
Documentation/admin-guide/mm/damon/usage.rst | 51 ++++++++++++++++-
2 files changed, 60 insertions(+), 2 deletions(-)
--- a/Documentation/admin-guide/mm/damon/start.rst~docs-admin-guide-mm-damon-document-damon-based-operation-schemes
+++ a/Documentation/admin-guide/mm/damon/start.rst
@@ -108,6 +108,17 @@ the results as separate image files. ::
You can view the visualizations of this example workload at [1]_.
Visualizations of other realistic workloads are available at [2]_ [3]_ [4]_.
+
+Data Access Pattern Aware Memory Management
+===========================================
+
+Below three commands make every memory region of size >=4K that doesn't
+accessed for >=60 seconds in your workload to be swapped out. ::
+
+ $ echo "#min-size max-size min-acc max-acc min-age max-age action" > scheme
+ $ echo "4K max 0 0 60s max pageout" >> scheme
+ $ damo schemes -c my_thp_scheme <pid of your workload>
+
.. [1] https://damonitor.github.io/doc/html/v17/admin-guide/mm/damon/start.html#visualizing-recorded-patterns
.. [2] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.png.html
.. [3] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.png.html
--- a/Documentation/admin-guide/mm/damon/usage.rst~docs-admin-guide-mm-damon-document-damon-based-operation-schemes
+++ a/Documentation/admin-guide/mm/damon/usage.rst
@@ -34,8 +34,8 @@ the reason, this document describes only
debugfs Interface
=================
-DAMON exports three files, ``attrs``, ``target_ids``, and ``monitor_on`` under
-its debugfs directory, ``<debugfs>/damon/``.
+DAMON exports four files, ``attrs``, ``target_ids``, ``schemes`` and
+``monitor_on`` under its debugfs directory, ``<debugfs>/damon/``.
Attributes
@@ -74,6 +74,53 @@ check it again::
Note that setting the target ids doesn't start the monitoring.
+Schemes
+-------
+
+For usual DAMON-based data access aware memory management optimizations, users
+would simply want the system to apply a memory management action to a memory
+region of a specific size having a specific access frequency for a specific
+time. DAMON receives such formalized operation schemes from the user and
+applies those to the target processes. It also counts the total number and
+size of regions that each scheme is applied. This statistics can be used for
+online analysis or tuning of the schemes.
+
+Users can get and set the schemes by reading from and writing to ``schemes``
+debugfs file. Reading the file also shows the statistics of each scheme. To
+the file, each of the schemes should be represented in each line in below form:
+
+ min-size max-size min-acc max-acc min-age max-age action
+
+Note that the ranges are closed interval. Bytes for the size of regions
+(``min-size`` and ``max-size``), number of monitored accesses per aggregate
+interval for access frequency (``min-acc`` and ``max-acc``), number of
+aggregate intervals for the age of regions (``min-age`` and ``max-age``), and a
+predefined integer for memory management actions should be used. The supported
+numbers and their meanings are as below.
+
+ - 0: Call ``madvise()`` for the region with ``MADV_WILLNEED``
+ - 1: Call ``madvise()`` for the region with ``MADV_COLD``
+ - 2: Call ``madvise()`` for the region with ``MADV_PAGEOUT``
+ - 3: Call ``madvise()`` for the region with ``MADV_HUGEPAGE``
+ - 4: Call ``madvise()`` for the region with ``MADV_NOHUGEPAGE``
+ - 5: Do nothing but count the statistics
+
+You can disable schemes by simply writing an empty string to the file. For
+example, below commands applies a scheme saying "If a memory region of size in
+[4KiB, 8KiB] is showing accesses per aggregate interval in [0, 5] for aggregate
+interval in [10, 20], page out the region", check the entered scheme again, and
+finally remove the scheme. ::
+
+ # cd <debugfs>/damon
+ # echo "4096 8192 0 5 10 20 2" > schemes
+ # cat schemes
+ 4096 8192 0 5 10 20 2 0 0
+ # echo > schemes
+
+The last two integers in the 4th line of above example is the total number and
+the total size of the regions that the scheme is applied.
+
+
Turning On/Off
--------------
_
Patches currently in -mm which might be from sj@xxxxxxxxxx are
maintainers-update-seongjaes-email-address.patch
mm-damon-core-print-kdamond-start-log-in-debug-mode-only.patch
mm-damon-core-account-age-of-target-regions.patch
mm-damon-core-implement-damon-based-operation-schemes-damos.patch
mm-damon-vaddr-support-damon-based-operation-schemes.patch
mm-damon-dbgfs-support-damon-based-operation-schemes.patch
mm-damon-schemes-implement-statistics-feature.patch
selftests-damon-add-schemes-debugfs-tests.patch
docs-admin-guide-mm-damon-document-damon-based-operation-schemes.patch
