Re: [PATCH RFC v4 2/3] sched: Avoid placing RT threads on cores handling long softirqs

[Joel Fernandes]

On Thu, Oct 20, 2022 at 02:47:54PM +0200, Alexander Gordeev wrote:
> On Wed, Oct 19, 2022 at 03:09:15PM -0700, John Stultz wrote:
> 
> Hi John,
> 
> [...]
> 
> > So I'll go ahead and simplify the check to just the LONG_SOFTIRQ_MASK
> > & (active | pending softirqs) check. This should avoid the need to
> > pull the cpu_rq(cpu)->curr value and simplify things.
> 
> In my reading of your approach if you find a way to additionally
> indicate long softirqs being handled by the remote ksoftirqd, it
> would cover all obvious/not-corner cases.

How will that help? The long softirq executing inside ksoftirqd will disable
preemption and prevent any RT task from executing.

Did I miss something?

thanks,

 - Joel