Re: [PATCH v2] sched/rt: Have RT_PUSH_IPI be default off for non PREEMPT_RT

[Tejun Heo <tj@kernel.org>]

Hello,

On Wed, May 20, 2026 at 03:02:44PM -0400, Steven Rostedt wrote:
> But it should still be making forward progress. The IPI handler is very short.
> 
> Are the other CPUs running very short lived RT tasks that constantly
> trigger the IPI push logic? I mean it would need to run a lot of RT
> tasks that keep going to sleep to cause a IPI storm to trigger.

I don't know for sure. At lower load level, there seem to a bit more than
1000 mpi3 irqs. The stalls were happening when load level was pushed up due
to maintenance going through the region. Let's be aggressive and say that
the rate was four times and each IRQ triggers the irq thread to be woken up
and go back to sleep. That'd be a transition out of RT every 250us across
the system. That's a lot but I'm not sure that's enough to stall for tens of
seconds. So, I'm not sure.

Thanks.

-- 
tejun