Re: [PATCH 4/6] sched_ext: Report preferred NUMA nodes through ops.set_numa_node()

[Peter Zijlstra <peterz@infradead.org>]

On Tue, Oct 27, 2026 at 05:13:33AM +0100, Andrea Righi wrote:

> @@ -4528,6 +4543,15 @@ static void __scx_enable_task(struct scx_sched *sch, struct task_struct *p)
>  
>  	if (SCX_HAS_OP(sch, set_weight))
>  		SCX_CALL_OP_TASK(sch, set_weight, rq, p, p->scx.weight);
> +
> +	if (SCX_HAS_OP(sch, set_numa_node)) {
> +		s32 nid = NUMA_NO_NODE;
> +
> +#ifdef CONFIG_NUMA_BALANCING
> +		nid = p->numa_preferred_nid;
> +#endif
> +		SCX_CALL_OP_TASK(sch, set_numa_node, rq, p, nid);
> +	}
>  }
>  
>  void scx_enable_task(struct scx_sched *sch, struct task_struct *p)
> @@ -4834,6 +4858,20 @@ void sched_ext_dead(struct task_struct *p)
>  	}
>  }
>  
> +#ifdef CONFIG_NUMA_BALANCING
> +static void numa_node_changed_scx(struct rq *rq, struct task_struct *p, int nid)
> +{
> +	struct scx_sched *sch = scx_task_sched(p);
> +
> +	if (task_dead_and_done(p) ||
> +	    scx_get_task_state(p) != SCX_TASK_ENABLED)
> +		return;
> +
> +	if (SCX_HAS_OP(sch, set_numa_node))
> +		SCX_CALL_OP_TASK(sch, set_numa_node, rq, p, nid);
> +}
> +#endif

I dont get this; why are you calling set_numa_mode() on enable? The
signal was sched_setnuma(), but now you're doing more.

Should not the existing enable method check p->numa_preferred_nid rather
than injecting this weird extra call?