Re: [Starpu-devel] StarPU MPI and Dags display

[Xavier Lacoste <xl64100@gmail.com>]

Ok, It seem I didn't submit all my graph some GEMMs are missing, this may 
explain both the wrong results and the strange dag.dot graph...

Sorry,

XL.

Le 27 févr. 2014 à 16:09, Xavier Lacoste <xl64100@gmail.com> a écrit :

> Hello,
> 
> I must do something wrong with my algorithme it does not give the right 
> solution with StarPU + MPI.
> 
> In my app i'm first submitting Task that will update local data using 
> remote data (GEMM).
> 
> Then I follow the local algorithm, submitting both tasks using only local 
> data (HETRF_TRSM + GEMM) and tasks updating remote data using local data 
> (GEMM).
> 
> When I look at the generated DAG I get a DAG that looks correct on one 
> processor.
> https://dl.dropboxusercontent.com/u/2234149/DAG_STARPU/DAG_OK.pdf
> 
> On two processors, the tasks from the "halo", submitted at the beginning 
> appears on top of the graph where they should follow some HETRF_TRSM (a 
> GEMM always depends on a HETRF_TRSM) :
> https://dl.dropboxusercontent.com/u/2234149/DAG_STARPU/DAG_KO.pdf
> 
> I guess the GEMM task at the beginning correspond to the 21 halo tasks 
> submitted at first step by proc 0 (On this case only data from proc 1 are 
> used to update data on proc 0, not the contrary)....
> The same tasks are submitted on proc 1 in the second submission part and 
> depends on HETRF_TRSM tasks (as I do nested task submission, HETRF_TRSM 
> should have even been run before GEMM are submitted)....
> 
> Are the dot graph reliable with MPI ?
> 
> My algorithm looks like this :
> 
> For each local column block c1
>   For each column block c2 used for updating c1
>      if c2 is not local submit_task(GEMM, c2, c1)
> 
> For each local column block c1
>   if (contribution(c1) == 0)
>      submit(HETRF_TRSM, c1)
> 
> HETRF_TRSM(c1) {
> 
> COMPUTATION
> 
> for each column block c2 updated by c1
>    submit_task(GEMM, c1, c2)
> }
> 
> GEMM(c1, c2) {
> 
> COMPUTATION
> 
> contribution(c1)--;
> If (contribution(c1)==0)
>   submit(HETRF_TRSM,c1);
> }
> 
> Does something looks wrong for you in this ?
> 
> (Here GEMM(...,c1) are not COMMUTABLE (because the STARPU_COMMUTE was not 
> available in starpu_mpi_task_build()) but they could be.)
> 
> Thanks,
> 
> XL.
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