How to do error checking in CUDA

Error checks in CUDA code can help catch CUDA errors at their source. There are 2 sources of errors in CUDA source code:

  1. Errors from CUDA API calls. For example, a call to cudaMalloc() might fail.
  2. Errors from CUDA kernel calls. For example, there might be invalid memory access inside a kernel.

All CUDA API calls return a cudaError value, so these calls are easy to check:

if ( cudaSuccess != cudaMalloc( &fooPtr, fooSize ) )
    printf( "Error!\n" );

CUDA kernel invocations do not return any value. Error from a CUDA kernel call can be checked after its execution by calling cudaGetLastError():

fooKernel<<< x, y >>>(); // Kernel call
if ( cudaSuccess != cudaGetLastError() )
    printf( "Error!\n" );

These two types of checks can be elegantly wrapped up in two simple error-checking functions like this:

Using these error checking functions is easy:

CudaSafeCall( cudaMalloc( &fooPtr, fooSize ) );

fooKernel<<< x, y >>>(); // Kernel call
CudaCheckError();

These functions are actually derived from similar functions which used to be available in the cutil.h in old CUDA SDKs.

Notice that the calls are inline functions, so absolutely no code is produced when CUDA_CHECK_ERROR is not defined. These utility functions can prove their worth to catch errors as close as possible to the error source only if they are used everywhere. So, use them to wrap all CUDA API calls and after all your kernel calls πŸ™‚

Tried with: CUDA 5.5

12 thoughts on “How to do error checking in CUDA

  1. Great! Made my work so much easier. Maybe you could explain to me what the do { … } while (0); part is for, I don’t seem to get that. And again, thanks!

    Liked by 1 person

    1. Johannes: Since the function will be inlined, a single “if” block can mix silently into an “else” or something else that follows in your code. The do-while prevents any such occurrence.

      Like

    2. Greg: Thanks for pointing out my misconception. I have removed the do-while and simplified the code now.

      Like

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