The patch titled
Subject: Docs/admin-guide/mm/damon/usage: document damos_before_apply tracepoint
has been added to the -mm mm-unstable branch. Its filename is
docs-admin-guide-mm-damon-usage-document-damos_before_apply-tracepoint.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/docs-admin-guide-mm-damon-usage-document-damos_before_apply-tracepoint.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: SeongJae Park <sj@xxxxxxxxxx>
Subject: Docs/admin-guide/mm/damon/usage: document damos_before_apply tracepoint
Date: Wed, 13 Sep 2023 02:20:50 +0000
Document damos_before_apply tracepoint on the usage document.
Link: https://lkml.kernel.org/r/20230913022050.2109-3-sj@xxxxxxxxxx
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/mm/damon/usage.rst | 37 +++++++++++++----
1 file changed, 30 insertions(+), 7 deletions(-)
--- a/Documentation/admin-guide/mm/damon/usage.rst~docs-admin-guide-mm-damon-usage-document-damos_before_apply-tracepoint
+++ a/Documentation/admin-guide/mm/damon/usage.rst
@@ -496,15 +496,24 @@ the files as above. Above is only for a
.. _tracepoint:
-Tracepoint for Monitoring Results
-=================================
+Tracepoints for Monitoring Results
+==================================
Users can get the monitoring results via the :ref:`tried_regions
-<sysfs_schemes_tried_regions>` or a tracepoint, ``damon:damon_aggregated``.
-While the tried regions directory is useful for getting a snapshot, the
-tracepoint is useful for getting a full record of the results. While the
-monitoring is turned on, you could record the tracepoint events and show
-results using tracepoint supporting tools like ``perf``. For example::
+<sysfs_schemes_tried_regions>`. The interface is useful for getting a
+snapshot, but it could be inefficient for fully recording all the monitoring
+results. For the purpose, two trace points, namely ``damon:damon_aggregated``
+and ``damon:damos_before_apply``, are provided. ``damon:damon_aggregated``
+provides the whole monitoring results, while ``damon:damos_before_apply``
+provides the monitoring results for regions that each DAMON-based Operation
+Scheme (:ref:`DAMOS <damon_design_damos>`) is gonna be applied. Hence,
+``damon:damos_before_apply`` is more useful for recording internal behavior of
+DAMOS, or DAMOS target access
+:ref:`pattern <damon_design_damos_access_pattern>` based query-like efficient
+monitoring results recording.
+
+While the monitoring is turned on, you could record the tracepoint events and
+show results using tracepoint supporting tools like ``perf``. For example::
# echo on > monitor_on
# perf record -e damon:damon_aggregated &
@@ -527,6 +536,20 @@ counter). Finally the tenth field (``X`
(refer to :ref:`design <damon_design_age_tracking>` for more details of the
counter).
+If the event was ``damon:damos_beofre_apply``, the ``perf script`` output would
+be somewhat like below::
+
+ kdamond.0 47293 [000] 80801.060214: damon:damos_before_apply: ctx_idx=0 scheme_idx=0 target_idx=0 nr_regions=11 121932607488-135128711168: 0 136
+ [...]
+
+Each line of the output represents each monitoring region that each DAMON-based
+Operation Scheme was about to be applied at the traced time. The first five
+fields are as usual. It shows the index of the DAMON context (``ctx_idx=X``)
+of the scheme in the list of the contexts of the context's kdamond, the index
+of the scheme (``scheme_idx=X``) in the list of the schemes of the context, in
+addition to the output of ``damon_aggregated`` tracepoint.
+
+
.. _debugfs_interface:
debugfs Interface (DEPRECATED!)
_
Patches currently in -mm which might be from sj@xxxxxxxxxx are
docs-admin-guide-mm-damon-usage-fixup-missed-ref-keyword.patch
docs-admin-guide-mm-damon-usage-place-debugfs-usage-at-the-bottom.patch
docs-admin-guide-mm-damon-usage-move-debugfs-intro-to-the-bottom-of-the-section.patch
docs-mm-damon-design-explicitly-introduce-nr_accesses.patch
docs-admin-guide-mm-damon-usage-explain-the-format-of-damon_aggregate-tracepoint.patch
docs-mm-damon-design-add-a-section-for-kdamond-and-damon-context.patch
docs-admin-guide-mm-damon-usage-link-design-doc-for-details-of-kdamond-and-context.patch
mm-damon-core-fix-a-comment-about-damon_set_attrs-call-timings.patch
mm-damon-core-add-more-comments-for-nr_accesses.patch
mm-damon-core-remove-duplicated-comment-for-watermarks-based-deactivation.patch
mm-damon-core-remove-struct-target-parameter-from-damon_aggregated-tracepoint.patch
mm-damon-core-add-a-tracepoint-for-damos-apply-target-regions.patch
docs-admin-guide-mm-damon-usage-document-damos_before_apply-tracepoint.patch
