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From:   Stefan Roesch <shr@devkernel.io>
To:     kernel-team@fb.com
Cc:     shr@devkernel.io, akpm@linux-foundation.org, david@redhat.com,
        hannes@cmpxchg.org, riel@surriel.com, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
Subject: [PATCH v4 3/4] mm/ksm: document smart scan mode
Date:   Wed, 27 Sep 2023 09:22:21 -0700
Message-Id: <20230927162222.3827551-4-shr@devkernel.io>
In-Reply-To: <20230927162222.3827551-1-shr@devkernel.io>
References: <20230927162222.3827551-1-shr@devkernel.io>
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This adds documentation for the smart scan mode of KSM.

Signed-off-by: Stefan Roesch <shr@devkernel.io>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
 Documentation/admin-guide/mm/ksm.rst | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Documentation/admin-guide/mm/ksm.rst b/Documentation/admin-g=
uide/mm/ksm.rst
index 776f244bdae4..2b38a8bb08af 100644
--- a/Documentation/admin-guide/mm/ksm.rst
+++ b/Documentation/admin-guide/mm/ksm.rst
@@ -155,6 +155,15 @@ stable_node_chains_prune_millisecs
         scan. It's a noop if not a single KSM page hit the
         ``max_page_sharing`` yet.
=20
+smart_scan
+        Historically KSM checked every candidate page for each scan. It =
did
+        not take into account historic information.  When smart scan is
+        enabled, pages that have previously not been de-duplicated get
+        skipped. How often these pages are skipped depends on how often
+        de-duplication has already been tried and failed. By default thi=
s
+        optimization is enabled. The ``pages_skipped`` metric shows how
+        effective the setting is.
+
 The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm=
/ksm/``:
=20
 general_profit
--=20
2.39.3