Re: [PATCH 1/2] sched_ext: Enable tick for finite slices on nohz_full

[Andrea Righi <arighi@nvidia.com>]

On Mon, Jul 06, 2026 at 12:09:36PM -1000, Tejun Heo wrote:
> Hello, Andrea.
> 
> Sashiko's first point looks real to me. The fix covers infinite->finite,
> but a finite slice landing on a nohz_full CPU after idle has the same
> issue whenever the previous run wasn't infinite (finite->idle->finite):
> the enqueue path already cleared TICK_DEP_BIT_SCHED against the idle
> rq->curr, and set_next_task_scx() re-asserts only on a slice-type
> transition, so with SCX_RQ_CAN_STOP_TICK unchanged the tick stays
> stopped.
> 
> set_next_task_scx() knows the incoming task, so it can assert directly
> rather than keying off the transition, like sched_fair_update_stop_tick()
> does for CFS. Moving the finite assertion out of the transition branch
> should do it:
> 
> 	if (p->scx.slice != SCX_SLICE_INF && tick_nohz_full_cpu(cpu_of(rq)))
> 		tick_nohz_dep_set_cpu(cpu_of(rq), TICK_DEP_BIT_SCHED);
> 
> Can you fold that in and add a finite->idle->finite selftest case for v2?

Yep, I'm currently looking/fixing at the issues found by Sashiko. I'll send a
v2 in a bit.

Thanks,
-Andrea