[ET Trac] #2844: HelloWorldCuda

[Anthony Shoup]

#2844: HelloWorldCuda

 Reporter: Anthony Shoup
   Status: submitted
Milestone: ET_2024_11
  Version: 
     Type: bug
 Priority: minor
Component: EinsteinToolkit thorn

The HelloWorldCuda thorn does not seem to work in my build of the Einstein Toolkit, ET\_2024\_11 release. The routine, HelloWorldCUDA\_evol, that launches the cuda kernel uses cctk\_lsh grid size values that are very large \(x-dir > 1x10^9\), which then tries to launch too many kernels.  Below is the code:

  extern "C"  
  void HelloWorldCUDA\_evol\(CCTK\_ARGUMENTS\)  
  \{  
    DECLARE\_CCTK\_ARGUMENTS;

```
const int val1 = cctk_iteration;
const int val2 = 3;
int res = 42;                 // poison

const dim3 blockDim(4, 4, 4);
```

//    const dim3 gridDim\(\(cctk\_lsh\[0\] \+ blockDim.x - 1\) / blockDim.x,  // Commented out by ALS  
//                       \(cctk\_lsh\[1\] \+ blockDim.y - 1\) / blockDim.y,  
//                       \(cctk\_lsh\[2\] \+ blockDim.z - 1\) / blockDim.z\);

```
// This code does work - ALS
const dim3 gridDim((8 + blockDim.x - 1) / blockDim.x,
                   (8 + blockDim.y - 1) / blockDim.y,
                   (8 + blockDim.z - 1) / blockDim.z);
add<<<gridDim, blockDim>>>(val1, val2, &res);

cudaError_t cerr = cudaDeviceSynchronize();  // Added by ALS
check_error(cerr, "Could not do cuda device synchronize"); // Added by ALS


CCTK_VInfo(CCTK_THORNSTRING, "CUDA says(testing): %d + %d = %d", val1, val2, res);
```

  \}

--
Ticket URL: https://bitbucket.org/einsteintoolkit/tickets/issues/2844/helloworldcuda
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