CUDA Memory Allocation Using cudaMalloc in C++

CUDA is an extension of C/C++ programming languages that allows programs to offload computationally intensive tasks to the GPU for parallel processing. Memory allocation is an important part of GPU programming, and the cudaMalloc function is used for allocating memory on the device.

cudaMalloc Function

The syntax for the cudaMalloc function is as follows:

cudaError_t cudaMalloc(void **devPtr, size_t size);

The first argument, devPtr, is a pointer to the allocated memory on the device, and the second argument, size, is the size in bytes of the memory allocation. The function returns a cudaError_t value that indicates the success or failure of the memory allocation.

Example Usage

Here is an example usage of cudaMalloc:

#include <cuda_runtime.h>
#include <cstdio>

int main() {
    int *devPtr;
    const int numElements = 1024;
    const int size = numElements * sizeof(int);
    cudaError_t err = cudaMalloc(&devPtr, size);
    if (err != cudaSuccess) {
        printf("CUDA error: %s\n", cudaGetErrorString(err));
        return -1;
    }

    // Use the allocated memory here...

    cudaFree(devPtr);
    return 0;
}

In this example, we allocate an array of 1024 integers on the GPU. We first calculate the size of the memory allocation (size) and pass that as the second argument to cudaMalloc. The first argument (devPtr) is a pointer to the allocated memory on the GPU, which we declare as an int*.

We then check the return value of cudaMalloc to make sure the memory allocation was successful. If there was an error, we print an error message and return -1.

After we use the allocated memory, we free it using the cudaFree function.

Conclusion

Memory allocation is a crucial part of GPU programming, and the cudaMalloc function is used for allocating memory on the device. In this brief introduction, we showed an example usage of cudaMalloc in C++, and discussed the syntax and return values of the function. Further reading and experimentation is recommended for those who wish to delve deeper.