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// SPDX-License-Identifier: BSD-3-Clause
/*
* p2_smem - shared-memory kernels:
* reduce_sum: 4096 int32 -> single sum, 16 blocks x 256 threads, shared
* tree reduction plus a global atomicAdd.
* gemm_tiled: 32x32 int32 GEMM with 16x16 shared-memory tiles,
* grid(2,2) x block(16,16).
*
* All arithmetic is exact in int32 (inputs are small non-negative ints), so
* device results must equal the CPU reference bit for bit.
* Device memory: in 16 KB, out 4 B, then A/B/C 4 KB each (peak 5 pages).
*/
#include "common.h"
#define R_N 4096
#define TS 16
#define M 32
#define K 32
#define NN 32
__global__ void reduce_sum(const int *in, int *out, int n)
{
__shared__ int sdata[256];
int tid = threadIdx.x;
int i = blockIdx.x * blockDim.x + tid;
sdata[tid] = (i < n) ? in[i] : 0;
__syncthreads();
for (int s = blockDim.x >> 1; s > 0; s >>= 1) {
if (tid < s)
sdata[tid] += sdata[tid + s];
__syncthreads();
}
if (tid == 0)
atomicAdd(out, sdata[0]);
}
__global__ void gemm_tiled(const int *A, const int *B, int *C)
{
__shared__ int As[TS][TS], Bs[TS][TS];
int row = blockIdx.y * TS + threadIdx.y;
int col = blockIdx.x * TS + threadIdx.x;
int sum = 0;
for (int t = 0; t < K / TS; t++) {
As[threadIdx.y][threadIdx.x] = A[row * K + t * TS + threadIdx.x];
Bs[threadIdx.y][threadIdx.x] = B[(t * TS + threadIdx.y) * NN + col];
__syncthreads();
for (int j = 0; j < TS; j++)
sum += As[threadIdx.y][j] * Bs[j][threadIdx.x];
__syncthreads();
}
C[row * NN + col] = sum;
}
int main(int argc, char **argv)
{
int *h_in = (int *)malloc(sizeof(int) * R_N);
int *h_A = (int *)malloc(sizeof(int) * M * K);
int *h_B = (int *)malloc(sizeof(int) * K * NN);
int *h_C = (int *)malloc(sizeof(int) * M * NN);
int red_sum = 0, gemm_sum = 0, bad = 0;
if (!h_in || !h_A || !h_B || !h_C)
return 1;
for (int i = 0; i < R_N; i++)
h_in[i] = i;
for (int i = 0; i < M * K; i++)
h_A[i] = i % 5;
for (int i = 0; i < K * NN; i++)
h_B[i] = i % 3;
for (int i = 0; i < R_N; i++)
red_sum += h_in[i];
for (int r = 0; r < M; r++)
for (int c = 0; c < NN; c++) {
int s = 0;
for (int t = 0; t < K; t++)
s += h_A[r * K + t] * h_B[t * NN + c];
h_C[r * NN + c] = s;
gemm_sum += s;
}
if (p2_emit_mode(argc, argv)) {
printf("RESULT smem reduce n=%d sum=%d bad=0\n", R_N, red_sum);
printf("RESULT smem gemm m=%d n=%d k=%d checksum=%d bad=0\n",
M, NN, K, gemm_sum);
free(h_in); free(h_A); free(h_B); free(h_C);
return p2_status(0);
}
p2_device_info();
int *d_in = NULL, *d_out = NULL, *d_A = NULL, *d_B = NULL, *d_C = NULL;
int got_sum = 0, got_gemm = 0;
P2_CHECK(cudaMalloc(&d_in, sizeof(int) * R_N));
P2_CHECK(cudaMalloc(&d_out, sizeof(int)));
P2_CHECK(cudaMemcpy(d_in, h_in, sizeof(int) * R_N,
cudaMemcpyHostToDevice));
P2_CHECK(cudaMemset(d_out, 0, sizeof(int)));
reduce_sum<<<(R_N + 255) / 256, 256>>>(d_in, d_out, R_N);
P2_CHECK(cudaGetLastError());
P2_CHECK(cudaDeviceSynchronize());
P2_CHECK(cudaMemcpy(&got_sum, d_out, sizeof(int),
cudaMemcpyDeviceToHost));
printf("RESULT smem reduce n=%d sum=%d bad=%d\n", R_N, got_sum,
got_sum == red_sum ? 0 : 1);
bad += (got_sum == red_sum) ? 0 : 1;
cudaFree(d_in); cudaFree(d_out);
P2_CHECK(cudaMalloc(&d_A, sizeof(int) * M * K));
P2_CHECK(cudaMalloc(&d_B, sizeof(int) * K * NN));
P2_CHECK(cudaMalloc(&d_C, sizeof(int) * M * NN));
P2_CHECK(cudaMemcpy(d_A, h_A, sizeof(int) * M * K,
cudaMemcpyHostToDevice));
P2_CHECK(cudaMemcpy(d_B, h_B, sizeof(int) * K * NN,
cudaMemcpyHostToDevice));
gemm_tiled<<<dim3(2, 2), dim3(TS, TS)>>>(d_A, d_B, d_C);
P2_CHECK(cudaGetLastError());
P2_CHECK(cudaDeviceSynchronize());
int *got_C = (int *)malloc(sizeof(int) * M * NN);
if (!got_C)
return 1;
P2_CHECK(cudaMemcpy(got_C, d_C, sizeof(int) * M * NN,
cudaMemcpyDeviceToHost));
int cbad = 0;
for (int i = 0; i < M * NN; i++) {
got_gemm += got_C[i];
if (got_C[i] != h_C[i])
cbad++;
}
printf("RESULT smem gemm m=%d n=%d k=%d checksum=%d bad=%d\n",
M, NN, K, got_gemm, cbad);
bad += cbad;
cudaFree(d_A); cudaFree(d_B); cudaFree(d_C);
free(got_C);
free(h_in); free(h_A); free(h_B); free(h_C);
return p2_status(bad);
}
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