Commit 3a4785c2 authored by SeongJae Park's avatar SeongJae Park Committed by Andrew Morton
Browse files

Docs/admin-guide/mm/damon/usage: document dests directory 

Document the newly added DAMOS action destination directory of the DAMON
sysfs interface on the usage document.

Link: https://lkml.kernel.org/r/20250709005952.17776-7-bijan311@gmail.com


Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
Cc: Bijan Tabatabai <bijantabatab@micron.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b9dfe8af

Documentation/admin-guide/mm/damon/usage.rst

+29 −4
Original line number Diff line number Diff line
@@ -85,6 +85,8 @@ comma (","). 
    │ │ │ │ │ │ │ :ref:`watermarks <sysfs_watermarks>`/metric,interval_us,high,mid,low

    │ │ │ │ │ │ │ :ref:`{core_,ops_,}filters <sysfs_filters>`/nr_filters

    │ │ │ │ │ │ │ │ 0/type,matching,allow,memcg_path,addr_start,addr_end,target_idx,min,max

    │ │ │ │ │ │ │ :ref:`dests <damon_sysfs_dests>`/nr_dests

    │ │ │ │ │ │ │ │ 0/id,weight

    │ │ │ │ │ │ │ :ref:`stats <sysfs_schemes_stats>`/nr_tried,sz_tried,nr_applied,sz_applied,sz_ops_filter_passed,qt_exceeds

    │ │ │ │ │ │ │ :ref:`tried_regions <sysfs_schemes_tried_regions>`/total_bytes

    │ │ │ │ │ │ │ │ 0/start,end,nr_accesses,age,sz_filter_passed
@@ -307,10 +309,10 @@ to ``N-1``. Each directory represents each DAMON-based operation scheme. 
schemes/<N>/

------------



In each scheme directory, seven directories (``access_pattern``, ``quotas``,

``watermarks``, ``core_filters``, ``ops_filters``, ``filters``, ``stats``, and

``tried_regions``) and three files (``action``, ``target_nid`` and

``apply_interval``) exist.

In each scheme directory, eight directories (``access_pattern``, ``quotas``,

``watermarks``, ``core_filters``, ``ops_filters``, ``filters``, ``dests``,

``stats``, and ``tried_regions``) and three files (``action``, ``target_nid``

and ``apply_interval``) exist.



The ``action`` file is for setting and getting the scheme's :ref:`action

<damon_design_damos_action>`.  The keywords that can be written to and read
@@ -484,6 +486,29 @@ Refer to the :ref:`DAMOS filters design documentation 
of different ``allow`` works, when each of the filters are supported, and

differences on stats.



.. _damon_sysfs_dests:



schemes/<N>/dests/

------------------



Directory for specifying the destinations of given DAMON-based operation

scheme's action.  This directory is ignored if the action of the given scheme

is not supporting multiple destinations.  Only ``DAMOS_MIGRATE_{HOT,COLD}``

actions are supporting multiple destinations.



In the beginning, the directory has only one file, ``nr_dests``.  Writing a

number (``N``) to the file creates the number of child directories named ``0``

to ``N-1``.  Each directory represents each action destination.



Each destination directory contains two files, namely ``id`` and ``weight``.

Users can write and read the identifier of the destination to ``id`` file.

For ``DAMOS_MIGRATE_{HOT,COLD}`` actions, the migrate destination node's node

id should be written to ``id`` file.  Users can write and read the weight of

the destination among the given destinations to the ``weight`` file.  The

weight can be an arbitrary integer.  When DAMOS apply the action to each entity

of the memory region, it will select the destination of the action based on the

relative weights of the destinations.



.. _sysfs_schemes_stats:



schemes/<N>/stats/