Make the description of stable_node_chains_prune_millisecs sysfs parameter
less implementation aware and add a few words about this parameter in the
"Design" section.
Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx>
---
Documentation/vm/ksm.rst | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/Documentation/vm/ksm.rst b/Documentation/vm/ksm.rst
index 00961b8..18d7c71 100644
--- a/Documentation/vm/ksm.rst
+++ b/Documentation/vm/ksm.rst
@@ -150,14 +150,12 @@ max_page_sharing
traversals are always schedule friendly themselves.
stable_node_chains_prune_millisecs
- How frequently to walk the whole list of stable_node "dups"
- linked in the stable_node "chains" in order to prune stale
- stable_nodes. Smaller milllisecs values will free up the KSM
- metadata with lower latency, but they will make ksmd use more
- CPU during the scan. This only applies to the stable_node
- chains so it's a noop if not a single KSM page hit the
- ``max_page_sharing`` yet (there would be no stable_node chains in
- such case).
+ specifies how frequently KSM checks the metadata of the pages
+ that hit the deduplication limit for stale information.
+ Smaller milllisecs values will free up the KSM metadata with
+ lower latency, but they will make ksmd use more CPU during the
+ scan. It's a noop if not a single KSM page hit the
+ ``max_page_sharing`` yet.
The effectiveness of KSM and MADV_MERGEABLE is shown in ``/sys/kernel/mm/ksm/``:
@@ -249,6 +247,11 @@ deduplication factor at the expense of slower worst case for rmap
walks for any KSM page which can happen during swapping, compaction,
NUMA balancing and page migration.
+The whole list of stable_node "dups" linked in the stable_node
+"chains" is scanned periodically in order to prune stale stable_nodes.
+The frequency of such scans is defined by
+``stable_node_chains_prune_millisecs`` sysfs tunable.
+
Reference
---------
.. kernel-doc:: mm/ksm.c
--
2.7.4
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