CUDA Academy · Lesson

The Copy Direction Enum

cudaMemcpyKind and getting it right.

The Fourth Argument

Every cudaMemcpy ends with a direction flag of type cudaMemcpyKind. It tells the runtime which way the bytes travel. 🧭

cudaMemcpy(dst, src, bytes, kind);

Use cudaMemcpyHostToDevice to upload inputs from CPU RAM into GPU memory before a kernel runs.

cudaMemcpy(d_a, h_a, bytes, cudaMemcpyHostToDevice);