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

[Alexander Gordeev]

On Mon, Nov 14, 2022 at 11:08:36PM -0800, John Stultz wrote:

Hi John,
...
> > Right. So the check to deem a remote CPU unfit would (logically) look like this:
> >
> > (active | pending | ksoftirqd) & LONG_SOFTIRQ_MASK
...
> As run_ksoftirqd() basically looks at the pending set and calls
> __do_softirq() which then moves the bits from the pending mask  to
> active mask while they are being run.
> 
> So (pending|active)&LONG_SOFTIRQ_MASK seems like it should be a
> sufficient check regardless of if the remote cpu is in softirq or
> ksoftirqd, no?

I did not realize run_ksoftirqd()->__do_softirq() covers it.
Sorry for the noise.

Thanks!

> thanks
> -john