Re: [PATCH] sched_ext: Document task ownership state machine

[Tejun Heo]

Hello,

On Wed, Mar 04, 2026 at 04:33:43PM +0100, Andrea Righi wrote:
> + * Task Ownership State Machine (sched_ext_entity->ops_state)
>   *
> + * The sched_ext core uses this state machine to track task ownership
> + * between the SCX core and the BPF scheduler. This allows the BPF
> + * scheduler to dispatch tasks without strict ordering requirements, while
> + * the SCX core safely rejects invalid dispatches.
>   *
> + * State Transitions
>   *
> + *       .------------> NONE (owned by SCX core)
> + *       |               |           ^
> + *       |       enqueue |           | direct dispatch
> + *       |               v           |
> + *       |           QUEUEING -------'
> + *       |               |
> + *       |       enqueue |
> + *       |     completes |
> + *       |               v
> + *       |            QUEUED (owned by BPF scheduler)
> + *       |               |           ^
> + *       |      dispatch |           | affinity changed
> + *       |               |           | (dispatch aborts)
> + *       |               v           |
> + *       |          DISPATCHING -----'
> + *       |               |
> + *       |      dispatch |
> + *       |     completes |
> + *       `---------------'

I don't think we transition tasks from DISPATCHING to QUEUED on affinity
changes. Not yet anyway, right?

Thanks.

-- 
tejun