Re: [Starpu-devel] [BUG] tests/datawizard/reclaim.c: hangs forever in task_wait_for_all when using OpenCL.

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

All,

hannibal has been acting weirdly last night. The buildbot profiles took 
much longer than normal to run and failed with segfaults in libcudart.

I am rebooting the machine, hoping it will reset the system in a proper 
state, you should re-run your program.

Cheers,

Nathalie

On 09/03/2012 03:29, Cyril Roelandt wrote:
> Hello,
>
> I am currently trying to write OpenCL versions of our CUDA codelets 
> for all the programs found in examples/ and tests/.
>
> It is going well so far, but I jave just stumbled upon the weirdest 
> bug in tests/datawizard/reclaim.c. I applied the following patch :
>
> --- tests/datawizard/reclaim.c  (revision 6089)
> +++ tests/datawizard/reclaim.c  (working copy)
> @@ -34,7 +34,7 @@
>  #  define BLOCK_SIZE (64*1024*1024)
>  #endif
>
> -static unsigned ntasks = 1000;
> +static unsigned ntasks = 1;
>
>  #ifdef STARPU_HAVE_HWLOC
>  static uint64_t get_total_memory_size(void)
> @@ -54,9 +54,9 @@
>
>  static struct starpu_codelet dummy_cl =
>  {
> -        .where = STARPU_CPU|STARPU_CUDA,
>         .cpu_funcs = {dummy_func, NULL},
>         .cuda_funcs = {dummy_func, NULL},
> +       .opencl_funcs = {dummy_func, NULL},
>         .nbuffers = 3,
>         .modes = {STARPU_RW, STARPU_R, STARPU_R}
>  };
>
> This patch is quite simple. It is worth noting that "dummy_func" is an 
> empty function: it could not be any dummier. I have changed the value 
> of ntasks because otherwise, the test takes quite a lot of time to run.
>
> When running this test on a CPU, everything works as expected :
>
> $ STARPU_NCPUS=1 STARPU_NCUDA=0 STARPU_NOPENCL=0 time -p 
> ./tests/datawizard/reclaim
> ...
> real 2.46
> user 0.02
> sys 1.98
>
> With CUDA, things start to take an awful lot of time :
>
> $ STARPU_NCPUS=0 STARPU_NCUDA=1 STARPU_NOPENCL=0 time -p 
> ./tests/datawizard/reclaim
> ...
> real 46.55
> user 33.84
> sys 15.13
>
> With OpenCL, the program just hangs for ever: the program is stuck in 
> starpu_task_wait_for_all().
>
> I've run all these commands on Hannibal.
>
> This reminds me of the bug Ludovic is currently struggling with : 
> starpu_task_wait_for_all() never returns, and he uses OpenCL kernels. 
> Ludovic, iirc, you started to debug this issue, so, could you tell us 
> more about it ?
>
> Cyril.
>
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