Docs/damon: document damos_migrate_{hot,cold}

This patch adds damon description for "migrate_hot" and "migrate_cold"
actions for both usage and design documents as long as a new
"target_nid" knob to set the migration target node.

[sj@kernel.org: trivial fixups for DAMOS_MIGRATE_{HOT,COLD} documentation]
  Link: https://lkml.kernel.org/r/20240618213630.84846-2-sj@kernel.org
Link: https://lkml.kernel.org/r/20240614030010.751-8-honggyu.kim@sk.comSigned-off-by: Honggyu Kim <honggyu.kim@sk.com>
Signed-off-by: SeongJae Park &lt;sj@kernel.org&gt;Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Gregory Price <gregory.price@memverge.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Hyeongtak Ji <hyeongtak.ji@sk.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

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

@@ -78,7 +78,7 @@ comma (",").
     │ │ │ │ │ │ │ │ ...
     │ │ │ │ │ │ ...
     │ │ │ │ │ :ref:`schemes <sysfs_schemes>`/nr_schemes
-    │ │ │ │ │ │ :ref:`0 <sysfs_scheme>`/action,apply_interval_us
+    │ │ │ │ │ │ :ref:`0 <sysfs_scheme>`/action,target_nid,apply_interval_us
     │ │ │ │ │ │ │ :ref:`access_pattern <sysfs_access_pattern>`/
     │ │ │ │ │ │ │ │ sz/min,max
     │ │ │ │ │ │ │ │ nr_accesses/min,max
@@ -289,14 +289,18 @@ schemes/<N>/
 ------------
 
 In each scheme directory, five directories (``access_pattern``, ``quotas``,
-``watermarks``, ``filters``, ``stats``, and ``tried_regions``) and two files
-(``action`` and ``apply_interval``) exist.
+``watermarks``, ``filters``, ``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
 from the file and their meaning are same to those of the list on
 :ref:`design doc <damon_design_damos_action>`.
 
+The ``target_nid`` file is for setting the migration target node, which is
+only meaningful when the ``action`` is either ``migrate_hot`` or
+``migrate_cold``.
+
 The ``apply_interval_us`` file is for setting and getting the scheme's
 :ref:`apply_interval <damon_design_damos>` in microseconds.
 

Documentation/mm/damon/design.rst

@@ -325,6 +325,10 @@ that supports each action are as below.
    Supported by ``paddr`` operations set.
  - ``lru_deprio``: Deprioritize the region on its LRU lists.
    Supported by ``paddr`` operations set.
+ - ``migrate_hot``: Migrate the regions prioritizing warmer regions.
+   Supported by ``paddr`` operations set.
+ - ``migrate_cold``: Migrate the regions prioritizing colder regions.
+   Supported by ``paddr`` operations set.
  - ``stat``: Do nothing but count the statistics.
    Supported by all operations sets.