Le Fri, Jul 10, 2026 at 11:28:11AM +0800, Jing Wu a écrit : > This series introduces Dynamic Housekeeping Management (DHM) to the Linux > kernel, enabling runtime reconfiguration of kernel-noise housekeeping > (nohz_full tick suppression, RCU NOCB offloading, and managed IRQ > migration) through the existing cgroup v2 cpuset isolated partition > mechanism — no new kernel ABI required. > > When a cpuset partition is set to isolated mode, DHM cycles each CPU in > that partition offline, reconfigures the housekeeping masks (removing the > CPU from HK_TYPE_KERNEL_NOISE and related types), and brings it back > online. The subsystems (tick/nohz, RCU NOCB, genirq) pick up the new > masks through their existing CPU hotplug callbacks. Destroying the > partition reverses the cycle: each CPU is taken offline, restored to all > housekeeping masks, and brought back online. > > Housekeeping cpumask pointers are RCU-protected to allow lock-free readers > during updates. A global dhm_cycling_cpus mask suppresses transient > cpuset partition invalidation while CPUs are being cycled. > > This work is related to Waiman Long's [PATCH-next 00/23] series > ([email protected]), which also targets runtime > cpuset housekeeping control. DHM's distinguishing feature is zero-boot- > parameter activation: nohz_full+nocb isolation can be achieved at runtime > without any boot-time nohz_full= or rcu_nocbs= parameters. > > Signed-off-by: Jing Wu <[email protected]> > Signed-off-by: Qiliang Yuan <[email protected]>
Sorry for the delay, I'm finally on it. One thing I would like to have is to make HK_TYPE_KERNEL_NOISE to always be a superset of HK_TYPE_DOMAIN. Ie: Cpuset's nohz_full should imply isolated domain partition. Or to put it another way: a nohz_full CPU should always run on isolated domains. If I could do it again, I would enforce the boot nohz_full= to always be a subset of isolcpus=domain. But we didn't know the possible usecase of it at the time. Thanks. -- Frederic Weisbecker SUSE Labs
