Re: [PATCH 6/6] rteval: Add --housekeeping option to reserve isolated CPUs

John Kacur
2026-04-20T21:42:31Z

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On Mon, 20 Apr 2026, Tomas Glozar wrote:

> pá 17. 4. 2026 v 21:51 odesílatel John Kacur <jkacur@redhat.com> napsal:
> >
> > Add a new --housekeeping option that allows users to specify isolated CPUs
> > that should be reserved for system housekeeping tasks and not used by
> > rteval's measurement or load modules.
> >
> > Key features:
> > - Validates that housekeeping CPUs are in the isolated CPU list (isolcpus)
> > - Detects conflicts with explicitly specified --measurement-cpulist or
> > --loads-cpulist options and exits with a clear error message
> > - Filters housekeeping CPUs from both measurement and load CPU lists
> > - Correctly excludes housekeeping CPUs from inverted CPU lists when only
> > one of measurement/loads is specified
> >
> > Example usage:
> > rteval --housekeeping 0-3 --measurement-run-on-isolcpus
> > Reserves isolcpus 0-3 for system tasks, runs measurements on
> > remaining isolated CPUs (4+) plus non-isolated CPUs
> >
> > Implementation:
> > - systopology.py: Add validate_housekeeping_cpus() function to validate
> > that housekeeping CPUs are in isolcpus
> > - rteval-cmd: Add --housekeeping argument, conflict checking, filtering,
> > and fix inversion logic to exclude housekeeping CPUs
> >
>
> This might be a good opportunity to additionally pin the rteval
> process to the housekeeping CPUs, as well as pass them to rtla's -H
> option.
>
> Tomas

You raise good points. Currently, housekeeping CPUs are for system tasks
like kernel threads, IRQs, etc., and the --housekeeping flag tells
rteval
not to touch these CPUs. For example, you might have CPUs 0-7 isolated,
and use 0-1 for housekeeping, and 2-7 for measurement threads which are
already pinned in rteval with sched_affinity.

However, we currently don't:
1. Pin the rteval process itself to housekeeping CPUs
2. Pass them to timerlat's -H option

These would be useful enhancements to improve isolation further. I'll
consider adding them in a future update.

Thanks for the suggestions!

John Kacur