Re: [PATCH] rcutorture: Traverse possible cpu to set maxcpu in rcu_nocb_toggle()

From: Paul E. McKenney
Date: Tue Aug 29 2023 - 08:39:43 EST


On Tue, Aug 29, 2023 at 11:24:24AM +0200, Frederic Weisbecker wrote:
> On Mon, Aug 28, 2023 at 05:51:09PM -0400, Joel Fernandes wrote:
> > I think the issue is the loop later in the function does
> > not try to toggle cpus that came online too late.
> >
> > So it does not test offloading on all CPUs just because max got updated too
> > late.
>
> Right, and therefore for_each_possible_cpu() or for_each_present_cpu()
> should be fine to iterate since it's ok to try to toggle an offline CPU.

OK, so I will accept the original patch which did just that.

Thank you!

I recently got burned by lack of workqueues on a not-yet-onlined CPU,
hence my questions here. ;-)

Thanx, Paul

> > One fix could be to periodically check in the loop if a new cpu at maxcpu + 1
> > ever got onlined. If it did, update the maxcpu.
>
> Is it worth the complication though?
>
> Thanks.
>
> >
> > Thanks.
> >
> >
> > >
> > > Thanks.