Re: [PATCH v2 3/3] lib/group_cpus.c: honor housekeeping config when grouping CPUs

Daniel Wagner
2024-07-01T07:08:41Z

On Sun, Jun 30, 2024 at 09:39:59PM GMT, Ming Lei wrote:
> > Make group_cpus_evenly aware of isolcpus configuration and use the
> > housekeeping CPU mask as base for distributing the available CPUs into
> > groups.
> >
> > Fixes: 11ea68f553e2 ("genirq, sched/isolation: Isolate from handling managed interrupts")
>
> isolated CPUs are actually handled when figuring out irq effective mask,
> so not sure how commit 11ea68f553e2 is wrong, and what is fixed in this
> patch from user viewpoint?

IO queues are allocated/spread on the isolated CPUs and if there is an
thread submitting IOs from an isolated CPU it will cause noise on the
isolated CPUs. The question is this a use case you need/want to support?
We have customers who are complaining that even with isolcpus provided
they still see IO noise on the isolated CPUs.