+ mm-ksm-document-smart-scan-mode.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/ksm: document smart scan mode
has been added to the -mm mm-unstable branch.  Its filename is
     mm-ksm-document-smart-scan-mode.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-ksm-document-smart-scan-mode.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Stefan Roesch <shr@devkernel.io>
Subject: mm/ksm: document smart scan mode
Date: Mon, 18 Sep 2023 11:58:15 -0700

This adds documentation for the smart scan mode of KSM.

Link: https://lkml.kernel.org/r/20230918185816.1518366-4-shr@devkernel.io
Signed-off-by: Stefan Roesch <shr@devkernel.io>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 Documentation/admin-guide/mm/ksm.rst |    9 +++++++++
 1 file changed, 9 insertions(+)

--- a/Documentation/admin-guide/mm/ksm.rst~mm-ksm-document-smart-scan-mode
+++ a/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.
 
+smart_scan
+        By default KSM checks every candidate page for each scan. It does
+        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 this
+        optimization is disabled. The ``pages_skipped`` metric shows how
+        effetive the setting is.
+
 The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm/ksm/``:
 
 general_profit
_

Patches currently in -mm which might be from shr@devkernel.io are

mm-ksm-add-smart-page-scanning-mode.patch
mm-ksm-add-pages_skipped-metric.patch
mm-ksm-document-smart-scan-mode.patch
mm-ksm-document-pages_skipped-sysfs-knob.patch