Docs/admin-guide/mm/damon/lru_sort: document addr_unit parameter

Commit 2e0fe9245d6b ("mm/damon/lru_sort: support addr_unit for
DAMON_LRU_SORT") introduced the 'addr_unit' parameter for DAMON_LRU_SORT.
But the usage document is not updated for that.  Update the document.

Link: https://lkml.kernel.org/r/20251026182216.118200-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/admin-guide/mm/damon/lru_sort.rst b/Documentation/admin-guide/mm/damon/lru_sort.rst
index 7b0775d281b48962f37c2263863eaf084fe3ea29..72a94320267683e91db3c95189733812defb9012 100644 (file)
--- a/Documentation/admin-guide/mm/damon/lru_sort.rst
+++ b/Documentation/admin-guide/mm/damon/lru_sort.rst
@@ -211,6 +211,28 @@ End of target memory region in physical address.
 The end physical address of memory region that DAMON_LRU_SORT will do work
 against.  By default, biggest System RAM is used as the region.
 
+addr_unit
+---------
+
+A scale factor for memory addresses and bytes.
+
+This parameter is for setting and getting the :ref:`address unit
+<damon_design_addr_unit>` parameter of the DAMON instance for DAMON_RECLAIM.
+
+``monitor_region_start`` and ``monitor_region_end`` should be provided in this
+unit.  For example, let's suppose ``addr_unit``, ``monitor_region_start`` and
+``monitor_region_end`` are set as ``1024``, ``0`` and ``10``, respectively.
+Then DAMON_LRU_SORT will work for 10 KiB length of physical address range that
+starts from address zero (``[0 * 1024, 10 * 1024)`` in bytes).
+
+Stat parameters having ``bytes_`` prefix are also in this unit.  For example,
+let's suppose values of ``addr_unit``, ``bytes_lru_sort_tried_hot_regions`` and
+``bytes_lru_sorted_hot_regions`` are ``1024``, ``42``, and ``32``,
+respectively.  Then it means DAMON_LRU_SORT tried to LRU-sort 42 KiB of hot
+memory and successfully LRU-sorted 32 KiB of the memory in total.
+
+If unsure, use only the default value (``1``) and forget about this.
+
 kdamond_pid
 -----------