Re: [Starpu-devel] [daxpy with StarPU-MPI]

[Nathalie Furmento <nathalie.furmento@labri.fr>]

Here some mistakes i found in your code.

* when allocating hx and hy, you should specify sizeof(starpu_data_handle_t) 
and not sizeof(starpu_data_handle_t*)

// allocate data handles
starpu_data_handle_t *hx = (starpu_data_handle_t *) 
malloc((size_t)NT*sizeof(starpu_data_handle_t));
starpu_data_handle_t *hy = (starpu_data_handle_t *) 
malloc((size_t)NT*sizeof(starpu_data_handle_t));

* you need to check if hx[i] and hy[i] are valid before calling 
starpu_data_unregister()

// unregister vector handles
for (int i = 0; i < NT; i++)
{
        if (hx[i]) starpu_data_unregister(hx[i]);
        if (hy[i]) starpu_data_unregister(hy[i]);
}

Everything else seems ok, let us know if it keeps failing, and more 
important, a backtrace of your segfault would be really useful. We cannot 
guess otherwise how it fails.

Cheers,

Nathalie

On oct. 17, 12:54, Maxim Abalenkov wrote:
> Dear Samuel et al.,
> 
> I hope all is well with you. Would you please be so kind to check the logic 
> of my StarPU-MPI “daxpy” code? I’m following the Handbook code snippet on 
> StarPU-MPI. I use two vectors x, y of length N=10 split into NT=5 segments 
> nb=2 elements each. Running on a single processor with mpiexec -np 1 
> ./tst_daxpy_mpi the first three segments are calculated correctly, while 
> the last two are unchanged. It seems there is a synchronisation issue. In 
> case I launch the code on two CPUs it crashes with a segmentation fault. 
> Thank you and have a good day ahead!
> 
> —