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#pragma once
#include <cuda_runtime.h>
#include <cublas_v2.h>
#include <stdio.h>
#include <stdlib.h>
template<const int BM,
const int BN,
const int BK,
const int TM>
__global__ void mysgemm_v3(int M, int N, int K, float alpha, float *A, float *B, float beta, float *C) {
int bx = blockIdx.x;
int by = blockIdx.y;
int thread_num = BM * BN / TM; // 一个线程负责block中计算TM个元素
int tx = threadIdx.x % BN;
int ty = threadIdx.x / BN * TM;
__shared__ float As[BM * BK];
__shared__ float Bs[BK * BN];
// 移动到当前block
A = &A[by * BM * K];
B = &B[bx * BN];
C = &C[by * BM * N + bx * BN];
/*
当前线程负责搬运全局内存中第a_tile_row行第a_tile_col列元素至共享内存第a_tile_row行第a_tile_col列
a_tile_stride表示block中线程可搬运a_tile_stride行至共享内存
若BM=64,BK=8,thread_num=512,则a_tile_stride=64,a_tile_stride=BM表示每个线程搬运一轮即可完成所需元素的搬运;
若BM=128,BK=8,thread_num=512,则a_tile_stride=64,表示每个线程搬运两轮即可完成所需元素的搬运;
*/
int a_tile_row = threadIdx.x / BK;
int a_tile_col = threadIdx.x % BK;
int a_tile_stride = thread_num / BK;
int b_tile_row = threadIdx.x / BN;
int b_tile_col = threadIdx.x % BN;
int b_tile_stride = thread_num / BN;
float tmp[TM + 1] = {0.}; // 每个线程负责TM个元素则需要申请TM个寄存器保存累加值额外的一个寄存器用于缓存
#pragma unroll
for (int k = 0; k < K; k += BK) {
#pragma unroll
for (int i = 0; i < BM; i += a_tile_stride) {
As[(a_tile_row + i) * BK + a_tile_col] = A[(a_tile_row + i) * K + a_tile_col];
}
#pragma unroll
for (int i = 0; i < BK; i += b_tile_stride) {
Bs[(b_tile_row + i) * BN + b_tile_col] = B[(b_tile_row + i) * N + b_tile_col];
}
__syncthreads();
A += BK;
B += BK * N;
#pragma unroll
for (int i = 0; i < BK; i++) {
tmp[TM] = Bs[tx + i * BN]; // 额外的一个寄存器避免反复从共享内存中读取Bs[tx + i * BN]
#pragma unroll // 循环展开,增加指令并行度
for (int j = 0; j < TM; j++) {
tmp[j] += As[(ty + j) * BK + i] * tmp[TM];
}
}
__syncthreads();
}
#pragma unroll
for (int j = 0; j < TM; j++) {
C[(ty + j) * N + tx] = alpha * tmp[j] + beta * C[(ty + j) * N + tx];
}
}