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@xxxxxxxxxxxx>
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@xxxxxxxxxxxx
Signed-off-by: Stefan Roesch <shr@xxxxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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@xxxxxxxxxxxx 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
