Document that creating a cpuset isolated partition updates the kernel-noise housekeeping masks (HK_TYPE_KERNEL_NOISE and HK_TYPE_MANAGED_IRQ) in addition to the sched-domain mask, and that destroying it restores the boot configuration.
No boot-time kernel parameters such as nohz_full= or rcu_nocbs= are required; writing "isolated" to cpuset.cpus.partition is the only mechanism needed. Co-developed-by: Qiliang Yuan <[email protected]> Signed-off-by: Qiliang Yuan <[email protected]> Signed-off-by: Jing Wu <[email protected]> --- Documentation/admin-guide/cgroup-v2.rst | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 6efd0095ed995..eaafe6d88c0e5 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -2721,6 +2721,23 @@ Cpuset Interface Files kernel boot command line option. If those CPUs are to be put into a partition, they have to be used in an isolated partition. + When an isolated partition is created or destroyed, the kernel + automatically drives runtime updates of the housekeeping masks + for kernel-noise types (nohz_full, RCU NOCB, managed IRQ + interrupts). This extends isolation beyond scheduler domains: + the tick is stopped on isolated CPUs, RCU callbacks are + offloaded to housekeeping cores, and managed interrupts are + migrated away. No boot-time kernel parameters such as + ``nohz_full=`` or ``rcu_nocbs=`` are required; writing + ``isolated`` to ``cpuset.cpus.partition`` is the only mechanism + needed. No additional cgroupfs files are required. + + CPUs with hotplug disabled (typically the boot CPU, CPU 0, on + x86-64) cannot be cycled offline for kernel-noise isolation. + The kernel emits a one-time warning and keeps those CPUs in + the tick and RCU-NOCB housekeeping set, even when they appear + in an isolated partition. + Device controller ----------------- -- 2.43.0
