Re: [starpu-devel] Follow-Up on Data Handle Scope and Task Scheduling

[Samuel Thibault <samuel.thibault@inria.fr>]

Xinbo Li, le ven. 18 avril 2025 00:44:39 +0000, a ecrit:
> In that case, if we define a data handle inside a local block and 
> unregister it
> immediately after task submission, any subsequent tasks — even if unrelated 
> —
> would be forced to wait for the earlier tasks to complete, due to the
> synchronization imposed by the unregister operation. This could potentially
> reduce efficiency.

Yes. That's why you'd prefer to just let starpu handle allocation by
passing a NULL pointer (and possibly use a task to initialize data in
it), and use starpu_data_unregister_submit after inserting all tasks
using it.

>     // Task 1
>     starpu_task_insert(
>         &some_codelet,
>         STARPU_RW, handle,
>         0);
> 
>     starpu_data_unregister(handle); // unregister at end of block
> }
> 
> // Task 2
> starpu_task_insert(
>     &some_other_codelet,
>     STARPU_RW, some_other_handle,
>     0);
> 
> In this case, would Task 2 be forced to wait for Task 1 to finish,

starpu_data_unregister waits for the completion of task 1, yes.

Samuel