Add docs for new interface cpuset.mems.migration, most of which
are stolen from cpuset(7) manpages.
Signed-off-by: Abel Wu <wuyun.abel@xxxxxxxxxxxxx>
---
Documentation/admin-guide/cgroup-v2.rst | 36 +++++++++++++++++++++++++
1 file changed, 36 insertions(+)
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index b1e81aa8598a..abf6589a390d 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -2079,6 +2079,42 @@ Cpuset Interface Files
Changing the partition state of an invalid partition root to
"member" is always allowed even if child cpusets are present.
+ cpuset.mems.migration
+ A read-write single value file which exists on non-root
+ cpuset-enabled cgroups.
+
+ Only the following migration modes are defined.
+
+ ======== ==========================================
+ "none" migration disabled [default]
+ "sync" move pages to cpuset nodes synchronously
+ "lazy" move pages to cpuset nodes on second touch
+ ======== ==========================================
+
+ By default, "none" mode is enabled. In this mode, once a page
+ is allocated (given a physical page of main memory) then that
+ page stays on whatever node it was allocated, so long as it
+ remains allocated, even if the cpusets memory placement policy
+ 'cpuset.mems' subsequently changes.
+
+ If "sync" mode is enabled in a cpuset, when the 'cpuset.mems'
+ setting is changed, any memory page in use by any process in
+ the cpuset that is on a memory node that is no longer allowed
+ will be migrated to a memory node that is allowed synchronously.
+ The relative placement of a migrated page within the cpuset is
+ preserved during these migration operations if possible.
+
+ The "lazy" mode is almost the same as "sync" mode, except that
+ it doesn't move the pages right away. Instead it sets these
+ pages to protnone, and numa faults triggered by second touching
+ these pages will handle the movement.
+
+ Furthermore, if a process is moved into a cpuset with migration
+ enabled ("sync" or "lazy" enabled), any memory pages it uses
+ that on memory nodes allowed in its previous cpuset, but which
+ are not allowed in its new cpuset, will be migrated to a memory
+ node allowed in the new cpuset.
+
Device controller
-----------------
--
2.31.1
