[cfe-dev] OpenMP offloaded target region executed in both host and target-device

Piyumi Lakshani via cfe-dev cfe-dev at lists.llvm.org
Mon Apr 9 08:56:41 PDT 2018


Thank you Alexey for pointing that out. I was able to successfully offload
the program to GPU after correcting that mistake.

On 9 April 2018 at 20:11, Alexey Bataev <a.bataev at outlook.com> wrote:

> Seems to me, your program crashes on GPU and then tries to execute the
> same code on cpu, though this behavior seems wrong to me.
> The problem is in your code. When you try to map A, B and E array, you're
> ding it it the wrong way. Instead of mapping the arrays you just map
> pointers to these arrays and do not allocate the memory for them on the
> GPU.
> -------------
> Best regards,
> Alexey Bataev
> 09.04.2018 8:21, Piyumi Lakshani via cfe-dev пишет:
> Hi,
> I'm working on a project which requires OpenMP offloading to Nvidia GPUs
> using Clang.
> System specification
> OS - Ubuntu 16.04 LTS
> Clang -version 4.00
> Processor - Intel(R) Core(TM) i7 -4700MQ CPU
> Cuda -version - 9.0
> Nvidia GPU - GeForce 740M (sm_capability - 35)
> But the problem is I when I execute a sample program to test OpenMP
> offloading to Nvidia GPUs, part of the target region tends to run in GPU
> and then same target region starts executing in the host.
> Please find the sample program  attached herewith, This a small C program
> written to multiply 2 matrices.
> The reason to claim that target region is being executed in both host and
> target-device is due to the abnormal output received from the print
> function residing in the target region. (My processor has 4 cores capable
> of handling 2 hardware level threads per core.).
> Please find the image of the command line output attached herewith.
> the program was compiled with -
>>  clang -fopenmp -fopenmp-targets=nvptx64-nvidia-cuda
> I can not figure out whether runtime believes that the GPU execution is
> not completing successfully?. So the target region is being executed in the
> host again.
> Thank you!
> --
> *Piyumi Rameshka*

*Piyumi Rameshka*
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