Re: [PATCH v8 5/6] workqueue: Imply strict CPU affinity for WQ_RT

[Tvrtko Ursulin]

On 05/11/2026 19:00, Tejun Heo wrote:
> Hello, Tvrtko.
>
> On Wed, Nov 04, 2026 at 09:52:24AM +0000, Tvrtko Ursulin wrote:
> > -	if (wq->flags & WQ_RT)
> > +	if (wq->flags & WQ_RT) {
> >   		attrs->prio = RT_PRIORITY;
> > +		/* Strict CPU affinity for low latency execution. */
> > +		attrs->affn_scope = WQ_AFFN_CPU;
> > +		attrs->affn_strict = true;
> > +	}
>
> I don't think this needs to be hard-coded. If setting it through
> workqueue attrs is too inconvenient, how about adding WQ_ flags so that
> the affinity scope and strictness can be set easily when the workqueue
> is created? The flags can be expanded to u64 to make room and
> reorganized cleanly while at it.

apply_workqueue_attrs() would work in theory but is not exported for 
modules which is required for panthor.

Regarding the flag reorganization, what would require expanding to u64? 
Unless I am missing something I see currently only 20 bits are used.

Although on a higher level my feeling is that panthor could first try 
with WQ_RT as is, and we consider adding strict affinity, via either of 
the above options, if that will not be good enough.

Regards,

Tvrtko