173 lines
5.2 KiB
Plaintext
173 lines
5.2 KiB
Plaintext
#include "mat_mul.h"
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#include <cstdio>
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#include <cuda_runtime.h>
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#define CUDA_CALL(f) \
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{ \
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cudaError_t err = (f); \
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if (err != cudaSuccess) { \
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fprintf(stderr, "CUDA error at [%s:%d] %d %s\n", __FILE__, __LINE__, \
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err, cudaGetErrorString(err)); \
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exit(1); \
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} \
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}
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#define MAX_NUM_GPU 4
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#define TS 32
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#define WPT 8
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#define RTS (TS/WPT)
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int num_devices = 4;
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__global__ void sgemm(float *A, float *B, float *C, int M, int N, int K) {
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int row = threadIdx.x;
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int col = threadIdx.y;
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int globalRow = (blockDim.x*WPT) * blockIdx.x + threadIdx.x;
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int globalCol = blockDim.y * blockIdx.y + threadIdx.y;
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__shared__ float Asub[TS][TS];
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__shared__ float Bsub[TS][TS];
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float acc[WPT];
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for (int w=0; w<WPT; w++) {
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acc[w] = 0.0f;
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}
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// Loop over all tiles
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const int numTiles = (K+TS-1)/TS;
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for (int t=0; t<numTiles; t++) {
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// Load one tile of A and B into local memory
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for (int w=0; w<WPT; w++) {
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const int tiledRow = TS*t + row;
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const int tiledCol = TS*t + col;
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if(globalRow + w*RTS >= M || tiledCol >= K)
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{
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Asub[row + w*RTS][col] = 0.0f;
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}
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else
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{
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Asub[row + w*RTS][col] = A[(globalRow + w*RTS)*K + tiledCol];
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int mm = (globalRow + w*RTS)*K;
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int kk = tiledCol;
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}
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if(tiledRow + w*RTS >=K || globalCol >=N)
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{
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Bsub[row + w*RTS][col] = 0.0f;
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}
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else
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{
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Bsub[row + w*RTS][col] = B[(tiledRow + w*RTS)*N + globalCol];
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}
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}
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// Synchronise to make sure the tile is loaded
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__syncthreads();
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// Perform the computation for a single tile
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for (int k=0; k<TS; k++) {
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for (int w=0; w<WPT; w++) {
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acc[w] += Asub[row + w*RTS][k] * Bsub[k][col];
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}
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}
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// Synchronise before loading the next tile
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__syncthreads();
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}
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// Store the final results in C
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for (int w=0; w<WPT; w++) {
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if (globalRow + w*RTS >= M || globalCol >=N) continue;
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C[(globalRow + w*RTS)*N + globalCol] = acc[w];
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}
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}
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// Array of device (GPU) pointers
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static float *a_d[MAX_NUM_GPU];
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static float *b_d[MAX_NUM_GPU];
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static float *c_d[MAX_NUM_GPU];
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static int M, N, K;
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static int Mbegin[MAX_NUM_GPU], Mend[MAX_NUM_GPU];
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void mat_mul(float *_A, float *_B, float *_C, int _M, int _N, int _K) {
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// Launch kernel on every GPU
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for (int i = 0; i < num_devices; i++) {
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dim3 blockDim(TS/WPT, TS, 1);
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dim3 gridDim(((Mend[i] - Mbegin[i]+TS-1)/TS), (N+TS-1)/TS, 1);
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CUDA_CALL( cudaSetDevice(i) );
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sgemm<<<gridDim, blockDim>>>(a_d[i], b_d[i], c_d[i], Mend[i] - Mbegin[i], N, K);
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}
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// DO NOT REMOVE; NEEDED FOR TIME MEASURE
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for (int i = 0; i < num_devices; i++) {
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CUDA_CALL( cudaSetDevice(i) );
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CUDA_CALL( cudaDeviceSynchronize() );
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}
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}
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void mat_mul_init(float *A, float *B, float *C, int _M, int _N, int _K) {
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M = _M, N = _N, K = _K;
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CUDA_CALL( cudaGetDeviceCount(&num_devices) );
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printf("Using %d devices\n", num_devices);
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for (int i = 0; i < num_devices; i++) {
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cudaDeviceProp prop;
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CUDA_CALL( cudaGetDeviceProperties(&prop, i) );
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printf("[GPU %d] %s\n", i, prop.name);
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}
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if (num_devices <= 0) {
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printf("No CUDA device found. Aborting\n");
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exit(1);
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}
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// Setup problem size for each GPU
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for (int i = 0; i < num_devices; i++) {
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Mbegin[i] = (M / num_devices) * i;
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Mend[i] = (M / num_devices) * (i + 1);
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}
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Mend[num_devices - 1] = M;
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// Allocate device memory for each GPU
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for (int i = 0; i < num_devices; i++) {
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CUDA_CALL( cudaSetDevice(i) );
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CUDA_CALL( cudaMalloc(&a_d[i], (Mend[i] - Mbegin[i]) * K * sizeof(float)) );
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CUDA_CALL( cudaMalloc(&b_d[i], K * N * sizeof(float)) );
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CUDA_CALL( cudaMalloc(&c_d[i], (Mend[i] - Mbegin[i]) * N * sizeof(float)) );
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}
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// Upload A and B matrix to every GPU
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for (int i = 0; i < num_devices; i++) {
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CUDA_CALL( cudaMemcpy(a_d[i], A + Mbegin[i] * K,(Mend[i] - Mbegin[i]) * K * sizeof(float), cudaMemcpyHostToDevice));
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CUDA_CALL( cudaMemcpy(b_d[i], B, K * N * sizeof(float), cudaMemcpyHostToDevice) );
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}
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// DO NOT REMOVE; NEEDED FOR TIME MEASURE
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for (int i = 0; i < num_devices; i++) {
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CUDA_CALL( cudaSetDevice(i) );
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CUDA_CALL( cudaDeviceSynchronize() );
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}
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}
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void mat_mul_final(float *A, float *B, float *C, int M, int N, int K) {
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// Do any post-matmul cleanup work here.
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// Download C matrix from GPUs
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for (int i = 0; i < num_devices; i++) {
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CUDA_CALL( cudaMemcpy(C + Mbegin[i] * N, c_d[i],(Mend[i] - Mbegin[i]) * N * sizeof(float), cudaMemcpyDeviceToHost));
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}
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// DO NOT REMOVE; NEEDED FOR TIME MEASURE
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for (int i = 0; i < num_devices; i++) {
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CUDA_CALL( cudaSetDevice(i) );
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CUDA_CALL( cudaDeviceSynchronize() );
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}
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}
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