[Openmp-dev] OpenMP target offload in a subprocess

[Ye Luo via Openmp-dev]

Looks like a CUDA thing. Google indicates MPS may help this issue but I had
no experience with MPS.
Ye
===================
Ye Luo, Ph.D.
Computational Science Division & Leadership Computing Facility
Argonne National Laboratory


On Fri, Jan 15, 2021 at 6:03 PM Christopher Daley via Openmp-dev <
openmp-dev at lists.llvm.org> wrote:

> Hi all,
>
> We are trying to use OpenMP target offload in a subprocess and get the
> following error:
>
> Target CUDA RTL --> Start initializing CUDA
> Target CUDA RTL --> Init requires flags to 1
> Target CUDA RTL --> Getting device 0
> Target CUDA RTL --> Error returned from cuDeviceGet
> Target CUDA RTL --> CUDA error is: initialization error
> Libomptarget error: Device 0 is not ready.
> Libomptarget error: run with env LIBOMPTARGET_INFO>1 to dump host-target
> pointer maps
> Libomptarget error: Build with debug information to provide more
> informationLibomptarget fatal error 1: failure of target construct while
> offloading is mandatory
>
> We are targeting a NVIDIA V100 GPU using a LLVM/Clang-12 build from
> December. We assume the error is because the CUDA context is started before
> there has been any OpenMP API calls or directives. How can we use OpenMP
> offload in the subprocess only? How can we use OpenMP offload in the
> original process and the subprocess? We have attached a toy code that fails
> with the message above when defining USE_CHILD_PROCESS. The key code is
> shown below:
>
> int main()
> {
>   int mypid = fork();
>   if( 0 == mypid ) {
> #ifdef USE_CHILD_PROCESS
>     printf("Calling from child process\n");
>     cfunc(); // contains OpenMP target offload
> #endif
>   } else {
> #ifndef USE_CHILD_PROCESS
>     printf("Calling from parent process\n");
>     cfunc(); // contains OpenMP target offload
> #endif
>   }
>   return 0;
> }
>
> Thanks,
> Chris
> _______________________________________________
> Openmp-dev mailing list
> Openmp-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/openmp-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/openmp-dev/attachments/20210115/a0c67146/attachment.html>