Re: [PATCH] net/sched: drr: reseed active class deficit after quantum changes

[Samuel Moelius]

On Tue, Jun 9, 2026 at 9:56 PM Jakub Kicinski <kuba@xxxxxxxxxx> wrote:
>
> On Tue,  9 Jun 2026 00:36:18 +0000 Samuel Moelius wrote:
> > Subject: [PATCH] net/sched: drr: reseed active class deficit after quantum changes
>
> If the change is not for a serious bug it needs to be generated against
> net-next. This was generated against Linus's tree I guess and doesn't
> apply to -next.
>
> > Changing the quantum of an active DRR class leaves the old deficit in
> > place.  The next scheduling round can therefore use credit accumulated
> > under a different quantum.
> >
> > This can be observed by making a class active, changing its quantum, and
> > then dequeuing with the old deficit still present.
> >
> > When an active class quantum changes, reseed its deficit from the new
> > quantum so the changed class weight is reflected immediately.
>
> TBH the current implementation is how I would expect DRR to work.
> quantum is the "refill" value, it should not reset the state of
> the current round? It wouldn't in an ASIC.
> --
> pw-bot: cr

I am getting ready to travel and I will address this when I return in
about two weeks. Thank you for understanding.