linux-kernel - [RFC PATCH 09/12] Docs/mm/damon/design: update for max_nr

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Message-ID: <20251123184329.85287-10-sj@kernel.org>
Date: Sun, 23 Nov 2025 10:43:23 -0800
From: SeongJae Park <sj@...nel.org>
To: 
Cc: SeongJae Park <sj@...nel.org>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...nel.org>,
	Jonathan Corbet <corbet@....net>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Michal Hocko <mhocko@...e.com>,
	Mike Rapoport <rppt@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	damon@...ts.linux.dev,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Subject: [RFC PATCH 09/12] Docs/mm/damon/design: update for max_nr_snapshots

Update DAMON design document for the newly added snapshot level DAMOS
deactivation feature, max_nr_snapshots.

Signed-off-by: SeongJae Park <sj@...nel.org>
---
 Documentation/mm/damon/design.rst | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Documentation/mm/damon/design.rst b/Documentation/mm/damon/design.rst
index 5cc7b7d662be..7fd819b8bbf7 100644
--- a/Documentation/mm/damon/design.rst
+++ b/Documentation/mm/damon/design.rst
@@ -720,6 +720,7 @@ scheme's execution.
 - ``qt_exceeds``: Total number of times the quota of the scheme has exceeded.
 - ``nr_snapshots``: Total number of DAMON snapshots that the scheme is tried to
   be applied.
+- ``max_nr_snapshots``: Upper limit of ``nr_snapshots``.
 
 "A scheme is tried to be applied to a region" means DAMOS core logic determined
 the region is eligible to apply the scheme's :ref:`action
@@ -741,6 +742,10 @@ to exclude anonymous pages and the region has only anonymous pages, or if the
 action is ``pageout`` while all pages of the region are unreclaimable, applying
 the action to the region will fail.
 
+Unlike normal stats, ``max_nr_snapshots`` is set by users.  If it is set as
+non-zero and ``nr_snapshots`` be same to or greater than ``nr_snapshots``, the
+scheme is deactivated.
+
 To know how user-space can read the stats via :ref:`DAMON sysfs interface
 <sysfs_interface>`, refer to :ref:s`stats <sysfs_stats>` part of the
 documentation.
-- 
2.47.3