Re: [PATCH v2 04/14] sched_ext: Use per-CPU DSQs instead of per-node global DSQs in bypass mode

Emil Tsalapatis
2025-11-10T23:26:31Z

Hi Tejun,

On Mon, Nov 10, 2025 at 4:59 PM Tejun Heo <tj@kernel.org> wrote:
>
> Hello, Emil.
>
> On Mon, Nov 10, 2025 at 04:43:23PM -0500, Emil Tsalapatis wrote:
> > > @@ -1298,7 +1298,7 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
> > >
> > > if (scx_rq_bypassing(rq)) {
> > > __scx_add_event(sch, SCX_EV_BYPASS_DISPATCH, 1);
> >
> > Nit: The bypass label has a single statement, and there is no fallthrough to it.
> > Can we just add the logic here:
> >
> > dsq = &task_rq(p)->scx.bypass_dsq;
> > goto enqueue;
> >
> > and remove the new label?
> >
> > > - goto global;
> > > + goto bypass;
> > > }
> > >
> > > if (p->scx.ddsp_dsq_id != SCX_DSQ_INVALID)
> > > @@ -1356,6 +1356,9 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
> > > global:
> > > dsq = find_global_dsq(sch, p);
> > > goto enqueue;
> > > +bypass:
> > > + dsq = &task_rq(p)->scx.bypass_dsq;
> >
> > Nit: If we keep the bypass label, we can remove the goto since the
> > label is right below. Otherwise, we could remove it
>
> This is really subjective but I like the fact that the local, global and
> bypass labels look symmetric. It doesn't make any different to compilers and
> I think keeping them so is less likely to trip up people.
>

Ack, makes total sense.

> Thanks.
>
> --
> tejun