Problem with using managed module variables from other files in Cuda Fortran

Accelerated Computing CUDA CUDA Programming and Performance
1

I have a managed variable in file p2.f95 in module a1 . I’m passing this managed variable to kernel in file p6.f95 .I am able to access the variable in file p6.f95 but unable to access the same from the kernel i.e; I am not able to print variable value from the device. Can someone please explain why…?

file1: p2.f95

module a1
    implicit none
    integer(kind=4),managed::lnode
end module a1

file2: p6.f95

module kernelsubroutine
    contains
    attributes(global) subroutine kernel(lnode)
        implicit none
        integer(kind=4)::lnode
        print*,"on device",lnode
    end subroutine kernel
end module kernelsubroutine

program main
    use a1
    use cudafor
    use kernelsubroutine
    implicit none
    integer(kind=4)::n
    lnode = 1
    print*,"on host",lnode
    call kernel<<<1,1>>>(lnode)
    n = cudaDeviceSynchronize()
end program main

compilation command 1: $pgf95 -Mcuda=rdc p2.f95 p6.f95

compilation command 2:

$pgf95 -Mcuda=rdc -c p2.f95

$pgf95 -Mcuda=rdc p6.f95 p2.o
p6.f95:

with both sets of compilation commands the output remains same

output command: $ cuda-memcheck ./a.out

output:

========= CUDA-MEMCHECK
 on host            1
========= Invalid __global__ read of size 4
=========     at 0x000010c8 in /home/vsriram/Documents/fortran_programs/p6.f95:11:kernelsubroutine_kernel_
=========     by thread (0,0,0) in block (0,0,0)
=========     Address 0x0060cf40 is out of bounds
=========     Saved host backtrace up to driver entry point at kernel launch time
=========     Host Frame:/usr/lib/x86_64-linux-gnu/libcuda.so [0x25428a]
=========     Host Frame:/opt/nvidia/hpc_sdk/Linux_x86_64/21.7/cuda/11.4/lib64/libcudart.so.11.0 [0x1402c]
=========     Host Frame:/opt/nvidia/hpc_sdk/Linux_x86_64/21.7/cuda/11.4/lib64/libcudart.so.11.0 (cudaLaunchKernel + 0x1d8) [0x67e58]
=========     Host Frame:/opt/nvidia/hpc_sdk/Linux_x86_64/21.7/compilers/lib/libcudafor.so (__pgiLaunchKernel + 0x1a6) [0x11194]
=========     Host Frame:./a.out [0x14f4]
=========     Host Frame:./a.out [0x1393]
=========
========= Program hit cudaErrorLaunchFailure (error 719) due to "unspecified launch failure" on CUDA API call to cudaDeviceSynchronize. 
=========     Saved host backtrace up to driver entry point at error
=========     Host Frame:/usr/lib/x86_64-linux-gnu/libcuda.so [0x355b43]
=========     Host Frame:/opt/nvidia/hpc_sdk/Linux_x86_64/21.7/cuda/11.4/lib64/libcudart.so.11.0 (cudaDeviceSynchronize + 0x127) [0x43217]
=========     Host Frame:/opt/nvidia/hpc_sdk/Linux_x86_64/21.7/compilers/lib/libcudafor_114.so (cudadevicesynchronize_ + 0x11) [0x7aca1]
=========     Host Frame:./a.out [0x14fb]
=========     Host Frame:./a.out [0x1393]
=========
========= ERROR SUMMARY: 2 errors
2

Hi @nmnethaji8
Looks like this question would be more suitable for other forum branches (e.g.: CUDA Programming and Performance - NVIDIA Developer Forums)

1 Like
3

I agree with you @AKravets,
Hope someone answers as soon as possible…!

4