[LTP] [PATCH v1 1/1] sched_football: harden kickoff synchronization on high-CPU systems

[John Stultz]

On Tue, Feb 24, 2026 at 2:45 AM Jan Polensky <japo@linux.ibm.com> wrote:
>
> The sched_football test has been intermittently failing, most noticeably
> on systems with many CPUs and/or under load, due to a startup ordering
> hole around kickoff.
>

I've not had time to closely review your suggestion here, but it
sounds reasonable.

That said, I want to warn you and ensure you are aware: the
RT_PUSH_IPI feature in the scheduler breaks the RT invariant
sched_football is testing.

I see this as a bug with that feature, but the scalability RT_PUSH_IPI
allows for seems more important to folks who are doing RT work then
the mis-behavior.  Steven and I talked awhile back about some ideas on
how we might be able to do the pull in a more efficient way while
still holding the invariant true, and I have a bug to track it, but
its not been high enough priority to get bandwidth yet.

So you might want to make sure you disable that feature before testing via:
# echo NO_RT_PUSH_IPI > /sys/kernel/debug/sched/features

thanks
-john