Document damos_before_apply tracepoint on the usage document. Signed-off-by: SeongJae Park <sj@xxxxxxxxxx> --- Documentation/admin-guide/mm/damon/usage.rst | 37 ++++++++++++++++---- 1 file changed, 30 insertions(+), 7 deletions(-) diff --git a/Documentation/admin-guide/mm/damon/usage.rst b/Documentation/admin-guide/mm/damon/usage.rst index 282062b6f134..6272cd36590a 100644 --- a/Documentation/admin-guide/mm/damon/usage.rst +++ b/Documentation/admin-guide/mm/damon/usage.rst @@ -496,15 +496,24 @@ the files as above. Above is only for an example. .. _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``) shows the ``age`` of the region (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!) -- 2.25.1