5–7 Oct 2026
Europe/Prague timezone

Enable runtime modification of nohz_full and managed_irq housekeeping CPUs

Not scheduled
20m
Scheduler and Real-Time MC Scheduler and Real-Time MC

Speaker

Mr Waiman Long (Red Hat)

Description

By using the cpuset isolated partition functionality in the Linux
kernel, users are now able to change the set of "isolcpus[=domain]"
HK_TYPE_DOMAIN housekeeping CPUs at runtime. This feature is used by
some Kubernetes based container orchestration platforms to enable the
creation of containers running latency sensitive workloads like DPDK.

Domain isolation by itself doesn't provide enough CPU isolation, so the
system has to be booted with a set of boot-time enabled nohz_full and
managed_irq isolated CPUs which are then combined with runtime domain
isolation to create the desired isolated CPUs for workloads that need
them. There are some wasted system overhead to have boot-time isolated
nohz_full and managed_irq CPUs that are not actually being used in
isolated cpuset partitons.

Eventually we would like to have nohz_full and managed_irq isolated
CPUs created at runtime when they are needed. This talk is about the
progress we have made in this direction and additional future works
that are needed to achieve this goal.

Author

Mr Waiman Long (Red Hat)

Presentation materials

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