# Final Exam Prep: Code

## CGMA Calculation

Compute to Global Memory Access (CGMA) ratio: The number of FP calculations performed for each access to the global memory within a region in a CUDA program.

A good CGMA is in the order of 20 or 30 to overcome slow global memory access.

### 2 Elements per Thread: C\[i] = A\[i] + B\[i]

Index of the first element:

```c
i = threadIdx.x + (blockIdx.x * blockdim.x)*2;
```

Index of the second element:

```c
i + blockDim.x
```