cpuset: Support RCU-NOCB toggle on v2 root partitions
Introduce a new "isolation.rcu_nocb" file within a cgroup2/cpuset
directory which provides support for a set of CPUs to either enable ("1")
or disable ("0") RCU callbacks offloading (aka. RCU NOCB). This can
overwrite previous boot settings towards "rcu_nocbs=" kernel parameter.
The file is only writeable on "root" type partitions to exclude any
overlap. The deepest root type partition has the highest priority.
This means that given the following setting:
Top cpuset (CPUs: 0-7)
cpuset.isolation.rcu_nocb = 0
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|
Subdirectory A (CPUs: 5-7)
cpuset.cpus.partition = root
cpuset.isolation.rcu_nocb = 0
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|
Subdirectory B (CPUs: 7)
cpuset.cpus.partition = root
cpuset.isolation.rcu_nocb = 1
the result is that only CPU 7 is in rcu_nocb mode.
Note that "rcu_nocbs" kernel parameter must be passed on boot, even
without a cpulist, so that nocb support is enabled.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Zefan Li <lizefan.x@bytedance.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Phil Auld <pauld@redhat.com>
Cc: Nicolas Saenz Julienne <nsaenz@kernel.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Waiman Long <longman@redhat.com>
Cc: Daniel Bristot de Oliveira <bristot@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
1 file changed
