Re: [PATCH 13/15] sched/isolation: Implement sysfs interface for dynamic housekeeping

[Waiman Long <longman@redhat.com>]

On 3/30/26 7:46 AM, Qiliang Yuan wrote:
> On Wed, Mar 25, 2026 at 03:04:32PM +0100, Peter Zijlstra wrote:
>> Why? What was wrong with cpusets?
> This is the central point of the architecture. The distinction I was
> trying to address is:
>
> 1. Task Isolation (Current CPUSets):
>     The `cpuset` subsystem (especially `cpuset.cpus.partition = isolated`)
>     is excellent at managing task placement and load balancing. It
>     ensures no user tasks are pushed to isolated CPUs.
>
> 2. Kernel Overhead Isolation (Housekeeping):
>     Currently, `cpusets` do not manage kernel-internal overhead like RCU
>     callbacks, timers, or unbound workqueues. These are managed by the
>     global `housekeeping_cpumask`, which is settled at boot via
>     `isolcpus`/`nohz_full` and is static.

My plan is to extend the cpuset isolated partition mechanism to isolate 
other kernel noise currently covered by the nohz_full and manged_irq 
boot command line. That will makes the HK_TYPE_KERNEL_NOISE cpumask 
modifiable at run time. It is not a direct modification of the HK 
cpumasks as advocated by this patch series but an indirect one via the 
creation of the appropriate isolated cpuset partitions.

Cheers,
Longman