diff --git a/OpenMP/linear-algebra/kernels/atax/atax.cu b/OpenMP/linear-algebra/kernels/atax/atax.cu index 5bfb264..cc6d9cb 100644 --- a/OpenMP/linear-algebra/kernels/atax/atax.cu +++ b/OpenMP/linear-algebra/kernels/atax/atax.cu @@ -17,96 +17,97 @@ #define M_PI 3.141 #endif -/* Array initialization. */ -static void init_array(int nx, int ny, DATA_TYPE POLYBENCH_2D(A, NX, NY, nx, ny), DATA_TYPE POLYBENCH_1D(x, NY, ny)) +/** + * Initialize the arrays to be used in the computation: + * + * - `x` is filled with multiples of `M_PI`; + * - `A` is filled with sample data. + * + * To be called on the CPU (uses the `__host__` qualifier). + */ +__host__ static void init_array(int nx, int ny, DATA_TYPE POLYBENCH_2D(A, NX, NY, nx, ny), DATA_TYPE POLYBENCH_1D(x, NY, ny)) { - int i, j; - - /// Initialize the `x` array with PI and its multiples. - for (i = 0; i < ny; i++) { + for (int i = 0; i < ny; i++) { x[i] = i * M_PI; } - /// Initialize the `A` matrix - for (i = 0; i < nx; i++) { - for (j = 0; j < ny; j++) { + for (int i = 0; i < nx; i++) { + for (int j = 0; j < ny; j++) { A[i][j] = ((DATA_TYPE)i * (j + 1)) / nx; } } } -/* DCE code. Must scan the entire live-out data. - Can be used also to check the correctness of the output. */ -static void print_array(int nx, DATA_TYPE POLYBENCH_1D(y, NX, nx)) +/** + * Print the given array. + * + * Cannot be parallelized, as the elements of the array should be + * + * To be called on the CPU (uses the `__host__` qualifier). + */ +__host__ static void print_array(int nx, DATA_TYPE POLYBENCH_1D(y, NX, nx)) { int i; - /// Print all numbers in the array sequentially. - // Cannot parallelize this: prints have to be sequential to make sense! for (i = 0; i < nx; i++) { fprintf(stderr, DATA_PRINTF_MODIFIER, y[i]); } fprintf(stderr, "\n"); } -/* Main computational kernel. The whole function will be timed, - including the call and return. */ -static void kernel_atax(int nx, int ny, DATA_TYPE POLYBENCH_2D(A, NX, NY, nx, ny), DATA_TYPE POLYBENCH_1D(x, NY, ny), DATA_TYPE POLYBENCH_1D(y, NY, ny)) -{ - int i, j; - for (i = 0; i < _PB_NY; i++) +/** + * Compute ATAX. + * + * Parallelizing this is the goal of the assignment. + * + * Currently to be called on the CPU (uses the `__host__` qualifier), but we may probably want to change that soon. + */ +__host__ static void kernel_atax(int nx, int ny, DATA_TYPE POLYBENCH_2D(A, NX, NY, nx, ny), DATA_TYPE POLYBENCH_1D(x, NY, ny), DATA_TYPE POLYBENCH_1D(y, NY, ny)) +{ + for (int i = 0; i < _PB_NY; i++) { y[i] = 0; + } - /// This computes... something? I guess whatever ATAX is? - // Now this gives a nice speedup, especially with a lot more threads than the count! - // THREAD_COUNT * 4 seems to be the best on my local computer. What's the best for the Jetson Nano? - for (i = 0; i < _PB_NX; i++) - { - /// Every iteration has its own tmp variable + for (int i = 0; i < _PB_NX; i++) { DATA_TYPE tmp = 0; - for (j = 0; j < _PB_NY; j++) { - /// Which gets increased by a bit on every iteration + for (int j = 0; j < _PB_NY; j++) { tmp += A[i][j] * x[j]; } - for (j = 0; j < _PB_NY; j++) { - /// Which is later used for to compute ATAX + for (int j = 0; j < _PB_NY; j++) { y[j] = y[j] + A[i][j] * tmp; } } } -int main(int argc, char **argv) +/** + * The main function of the benchmark, which sets up tooling to measure the time spent computing `kernel_atax`. + * + * We should probably avoid editing this. + */ +__host__ int main(int argc, char **argv) { - /* Retrieve problem size. */ int nx = NX; int ny = NY; - /* Variable declaration/allocation. */ POLYBENCH_2D_ARRAY_DECL(A, DATA_TYPE, NX, NY, nx, ny); POLYBENCH_1D_ARRAY_DECL(x, DATA_TYPE, NY, ny); POLYBENCH_1D_ARRAY_DECL(y, DATA_TYPE, NY, ny); - /* Initialize array(s). */ init_array(nx, ny, POLYBENCH_ARRAY(A), POLYBENCH_ARRAY(x)); - /* Start timer. */ polybench_start_instruments; - /* Run kernel. */ kernel_atax(nx, ny, POLYBENCH_ARRAY(A), POLYBENCH_ARRAY(x), POLYBENCH_ARRAY(y)); - /* Stop and print timer. */ polybench_stop_instruments; polybench_print_instruments; - /* Prevent dead-code elimination. All live-out data must be printed - by the function call in argument. */ + /* Prevent dead-code elimination. All live-out data must be printed by the function call in argument. */ polybench_prevent_dce(print_array(nx, POLYBENCH_ARRAY(y))); - /* Be clean. */ POLYBENCH_FREE_ARRAY(A); POLYBENCH_FREE_ARRAY(x); POLYBENCH_FREE_ARRAY(y);