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| author | Mike Rapoport <rppt@linux.vnet.ibm.com> | 2018-04-24 08:40:26 +0200 |
|---|---|---|
| committer | Jonathan Corbet <corbet@lwn.net> | 2018-04-28 01:19:40 +0200 |
| commit | 2a695ca412943b88abde5dda0d5b6876fd154ac8 (patch) | |
| tree | f5c092dab193055bcbf701693ea785c89dde2511 /Documentation/vm | |
| parent | docs/vm: ksm: reshuffle text between "sysfs" and "design" sections (diff) | |
| download | linux-2a695ca412943b88abde5dda0d5b6876fd154ac8.tar.xz linux-2a695ca412943b88abde5dda0d5b6876fd154ac8.zip | |
docs/vm: ksm: update stable_node_chains_prune_millisecs description
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@linux.vnet.ibm.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Diffstat (limited to 'Documentation/vm')
| -rw-r--r-- | Documentation/vm/ksm.rst | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/Documentation/vm/ksm.rst b/Documentation/vm/ksm.rst index 00961b8ab03e..18d7c710a5f3 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 |