[RFC PATCH 7/8] cgroup/cpuset: Document the new cpuset.cpus.isolation_full control file

Waiman Long
2024-01-17T16:36:21Z

Document the new cpuset.cpus.isolation_full control file. Currently only
the rcu_nocbs flag is supported, but more will be added in the future.

Signed-off-by: Waiman Long <longman@redhat.com>
---
Documentation/admin-guide/cgroup-v2.rst | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 17e6e9565156..bbd066838f93 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -2352,6 +2352,30 @@ Cpuset Interface Files
isolated partitions. It will be empty if no isolated partition
is created.

+ cpuset.cpus.isolation_full
+ A read multiple values and write single value file which exists
+ on root cgroup only.
+
+ This file shows the state of full CPU isolation mode for isolated
+ CPUs in isolated partitions. It shows either "0' if full CPU
+ isolation mode is disabled, or "1" followed by a comma-separated
+ list of additional CPU isolation flags that are enabled.
+ The currently supported CPU isolation flag is:
+
+ rcu_nocbs
+ RCU no-callback CPU mode, which prevents such CPUs'
+ callbacks from being invoked in softirq context.
+ Invocation of such CPUs' RCU callbacks will instead be
+ offloaded to "rcuox/N" kthreads created for that purpose.
+ It is similar in functionality to the "rcu_nocbs"
+ boot command line option, but for dynamically created
+ isolated CPUs in isolated partitions. This flag can
+ only be enabled if such a "rcu_nocbs" option is present
+ in the boot command line of the running kernel.
+
+ Full CPU isolation mode is enabled by writing a non-zero value
+ to this file and disabled by writing a zero value to it.
+
cpuset.cpus.partition
A read-write single value file which exists on non-root
cpuset-enabled cgroups. This flag is owned by the parent cgroup
--
2.39.3