[Starpu-devel] StarPU fails when using dmda/pheft with more than 1 GPU

[David Pereira <david_sape@hotmail.com>]

Hi everyone,

I have a problem which I cannot identify. When using the "pheft" or "dmda" schedulers using

only one GPU (STARPU_NCUDA=1), the program runs smoothly, but when I use the two GPUs that I have,

an unspecified launch failure occurs from a kernel launched by a task. This error happens sometimes in one kernel but may also happen in other kernels.

The "dm", "eager" and "peager" don't have this problem.

Any ideia what the problem could be? I'm using StarPU 1.1.3 (but the problem occured in previous versions as well).

Also, is it possible that a CUDA program runs faster when using StarPU (using one GPU) than

running the program without the framework? The StarPU version has parallel tasks unlike the version

without the framework (which does not use streams). I'm thinking that StarPU may be launching concurrent kernels... Is that right?

Last question, how can I know if GPUDirect is been used? I was analyzing information from Vite and I think the transfers goes from a GPU

global memory to RAM first before going to the other GPU.

Thanks in advance!

Kind regards,

--

David Pereira