API Extensions

SCALE has some runtime/library features not found in NVIDIA's CUDA Toolkit.

Environment variables

Some extra features can be enabled by environment variables.

SCALE_EXCEPTIONS

Errors from the CUDA API can be hard to debug, since they simply return an error code that the host program has to do something with.

SCALE provides an environment variable to make any error from the CUDA API produce a observable result.

Setting SCALE_EXCEPTIONS=1 will cause all CUDA APIs to throw descriptive exceptions instead of returning C-style error codes.

Setting SCALE_EXCEPTIONS=2 will print the error messages to stderr, but not throw them. This is helpful for programs that deliberately create CUDA errors as part of their processing.

In cases where CUDA APIs are expected to return a value other than cudaSuccess during normal operation (such as cudaStreamQuery(), an exception will not be thrown except if an exceptional case arises.

API Extensions

Some of SCALE's API extensions require the scale.h header to be included.

Programmatic Exception Enablement

SCALE exceptions (see documentation of SCALE_EXCEPTIONS environment variable above) may also be enabled/disabled programmatically using:

scale::Exception::enable(); // To enable.
scale::Exception::enable(false); // To disable.

Even when exceptions are disabled, you can access a scale::Exception object containing the descriptive error message from the most recent failure using scale::Exception::last():

cudaError_t e = cudaSomething();
if (e != cudaSuccess) {
    const scale::Exception &ex = scale::Exception::last();
    std::cerr << "CUDA error: " << ex.what() << '\n';
}

The error accessed by this API is the same one you'd get from using the CUDA API cudaGetLastError(), just more descriptive.