Re: [Starpu-devel] Performance issues when specifying const and __attribute__ ((output))

[ludovic.courtes@inria.fr (Ludovic Courtès)]

Hi Mehdi,

Mehdi AMINI <mehdi.amini@silkan.com> skribis:

> I have a quite simple code :
>
>    /* Start timer. */
>    timer_start();
>
>    p4a_launcher_main(s, ny);
>    p4a_launcher_main_1((double *)A, p, q, nx, ny);
>    for(i = 0; i <= nx-1; i += 1) {
>       double r_0 = r[i];
>       p4a_launcher_main_2((double *)A, s, i, ny, r_0);
>    }
>    /* Stop and print timer. */
>    #pragma starpu unregister s
>    #pragma starpu unregister q
>    timer_stop_display();
>
> A,r,s,p,q are arrays registered to StarPU. The p4a_launcher_xxxx
> functions are tasks that launch very simple CUDA kernel. A CPU
> implementation is also given but is avoided at runtime using
> STARPU_NCPUS environment variable.
>
>
>
> I tried to make use of "const" qualifier and "__attribute__((output))"
> on task parameter to hint StarPU about the data transfer.

In addition to what Samuel asked, could you send the declaration of the
p4a_launcher_* tasks and task implementations?

Thanks,
Ludo’.