CUDA：填充主要列矩阵
[英]CUDA: Filling a column-major matrix
问题描述
我对CUDA相当陌生，并且我正尝试将我为性能关键型项目所做的一些繁琐的计算工作卸载到GPU。 在我的计算机上，我有两张NVS 510图形卡，但是我目前只在尝试其中一张。
我有一些要填充的大型列矩阵（1000-5000行x 1-5 M列）。 到目前为止，我能够像编写数组一样编写代码来填充矩阵，并且它对于较小尺寸的矩阵也能很好地工作。
__global__ void interp_kernel(fl_type * d_matrix, fl_type* weights, [other params],
int n_rows, int num_cols) {
int index = blockIdx.x * blockDim.x + threadIdx.x;
int column = index / n_rows;
int row = index % n_rows;
if (row > n_sim || column > num_cols) return;
d_matrix[index] = …something(row, column,[other params]);
}
内核称为：
fl_type *res;
cudaMalloc((void**)&res, n_columns*n_rows*fl_size);
int block_size = 1024;
int num_blocks = (n_rows* n_columns + block_size - 1) / block_size;
std::cout << "num_blocks:" << num_blocks << std::endl;
interp_kernel << < num_blocks, block_size >> > (res,[other params], n_rows,n_columns);
一切都很好。 如果我更改内核以使用2D线程：
__global__ void interp_kernel2D(fl_type * d_matrix, fl_type* weights, [other params],
int n_rows, int num_cols) {
int column = blockIdx.x * blockDim.x + threadIdx.x;
int row = blockIdx.y * blockDim.y + threadIdx.y;
int index = column* n_rows + row;
if (row > n_rows || column > num_cols) return;
d_matrix[index] = …something(row, column,[other params]);
}
我调用它
int block_size2 = 32; //each block will have block_size2*block_size2 threads
dim3 num_blocks2(block_size2, block_size2);
int x_grid = (n_columns + block_size2 - 1) / block_size2;
int y_grid = (n_rows + block_size2 - 1) / block_size2;
dim3 grid_size2(x_grid, y_grid);
interp_kernel2D <<< grid_size2, num_blocks2 >>> (res,[other params], n_rows,n_columns);
结果全为零，CUDA返回未知错误。 我想念什么？ 可以在此处找到使用VS2015和CUDA 8.0编译时没有错误的实际代码： https ://pastebin.com/XBCVC7VV
这是pastebin链接中的代码：
#include "cuda_runtime.h"
#include "device_launch_parameters.h"
#include <stdio.h>
#include <assert.h>
#include <iostream>
#include <random>
#include <chrono>
typedef float fl_type;
typedef int pos_type;
typedef std::chrono::milliseconds ms;
//declaration of the cuda function
void cuda_interpolation_function(fl_type* interp_value_back, int result_size, fl_type * grid_values, int grid_values_size, fl_type* weights, pos_type* node_map, int total_action_number, int interp_dim, int n_sim);
fl_type iterp_cpu(fl_type* weights, pos_type* node_map, fl_type* grid_values, int& row, int& column, int& interp_dim, int& n_sim) {
int w_p = column*interp_dim;
fl_type res = weights[w_p] * grid_values[row + node_map[w_p] * n_sim];
for (int inter_point = 1; inter_point < interp_dim; inter_point++) {
res += weights[w_p + inter_point] * grid_values[node_map[w_p + inter_point] * n_sim + row];
}
return res;
}
__global__ void interp_kernel(fl_type * d_matrix, fl_type* weights, pos_type* node_map, fl_type* grid_values, int interp_dim, int n_sim, int num_cols) {
int index = blockIdx.x * blockDim.x + threadIdx.x;
int column = index / n_sim;
int row = index % n_sim;
int w_p = column*interp_dim;
if (row > n_sim || column > num_cols) return;
fl_type res = weights[w_p] * grid_values[row + node_map[w_p] * n_sim];
for (int inter_point = 1; inter_point < interp_dim; inter_point++) {
res += weights[w_p + inter_point] * grid_values[row + node_map[w_p + inter_point] * n_sim];
}
d_matrix[index] = res;
}
__global__ void interp_kernel2D(fl_type * d_matrix, fl_type* weights, pos_type* node_map, fl_type* grid_values, int interp_dim, int n_sim, int num_cols) {
int column = blockIdx.x * blockDim.x + threadIdx.x;
int row = blockIdx.y * blockDim.y + threadIdx.y;
int index = column*n_sim + row;
int w_p = column*interp_dim;
if (row > n_sim || column > num_cols) return;
fl_type res = weights[w_p] * grid_values[row + node_map[w_p] * n_sim];
for (int inter_point = 1; inter_point < interp_dim; inter_point++) {
res += weights[w_p + inter_point] * grid_values[row + node_map[w_p + inter_point] * n_sim];
}
d_matrix[index] = res;
}
void verify(fl_type *host, fl_type *device, int size) {
int count = 0;
int count_zero = 0;
for (int i = 0; i < size; i++) {
if (host[i] != device[i]) {
count++;
//std::cout <<"pos: " <<i<< " CPU:" <<h[i] << ", GPU: " << d[i] <<std::endl;
assert(host[i] == device[i]);
if (device[i] == 0.0)
count_zero++;
}
}
if (count) {
std::cout << "Non matching: " << count << "out of " << size << "(" << (float(count) / size * 100) << "%)" << std::endl;
std::cout << "Zeros returned from the device: " << count_zero <<"(" << (float(count_zero) / size * 100) << "%)" << std::endl;
}
else
std::cout << "Perfect match!" << std::endl;
}
int main() {
int fl_size = sizeof(fl_type);
int pos_size = sizeof(pos_type);
int dim = 5; // range: 2-5
int number_nodes = 5500; // range: 10.000-500.000
int max_actions = 12; // range: 6-200
int n_sim = 1000; // range: 1.000-10.000
int interp_dim = std::pow(2, dim);
int grid_values_size = n_sim*number_nodes;
std::default_random_engine generator;
std::normal_distribution<fl_type> normal_dist(0.0, 1);
std::uniform_int_distribution<> uniform_dist(0, number_nodes - 1);
double bit_allocated = 0;
fl_type * grid_values; //flattened 2d array, containing the value of the grid (n_sims x number_nodes)
grid_values = (fl_type *)malloc(grid_values_size * fl_size);
bit_allocated += grid_values_size * fl_size;
for (int i = 0; i < grid_values_size; i++)
grid_values[i] = normal_dist(generator);
pos_type * map_node2values_start; //vector that maps each node to the first column of the result matrix regarding that done
pos_type * map_node2values_how_many; //vector that stores how many action we have per node
map_node2values_start = (pos_type *)malloc(number_nodes * pos_size);
map_node2values_how_many = (pos_type *)malloc(number_nodes * pos_size);
bit_allocated += 2 * (number_nodes * pos_size);
for (int i = 0; i < number_nodes; i++) {
//each node as simply max_actions
map_node2values_start[i] = max_actions*i;
map_node2values_how_many[i] = max_actions;
}
//total number of actions, which is amount of column of the results
int total_action_number = map_node2values_start[number_nodes - 1] + map_node2values_how_many[number_nodes - 1];
//vector that keep tracks of the columnt to grab, and their weight in the interpolation
fl_type* weights;
pos_type * node_map;
weights = (fl_type *)malloc(total_action_number*interp_dim * pos_size);
bit_allocated += total_action_number * fl_size;
node_map = (pos_type *)malloc(total_action_number*interp_dim * pos_size);
bit_allocated += total_action_number * pos_size;
//filling with random numbers
for (int i = 0; i < total_action_number*interp_dim; i++) {
node_map[i] = uniform_dist(generator); // picking random column
weights[i] = 1.0 / interp_dim; // uniform weights
}
std::cout << "done filling!" << std::endl;
std::cout << bit_allocated / 8 / 1024 / 1024 << "MB allocated" << std::endl;
int result_size = n_sim*total_action_number;
fl_type *interp_value_cpu;
bit_allocated += result_size* fl_size;
interp_value_cpu = (fl_type *)malloc(result_size* fl_size);
auto start = std::chrono::steady_clock::now();
for (int row = 0; row < n_sim; row++) {
for (int column = 0; column < total_action_number; column++) {
auto zz = iterp_cpu(weights, node_map, grid_values, row, column, interp_dim, n_sim);
interp_value_cpu[column*n_sim + row] = zz;
}
}
auto elapsed_cpu = std::chrono::steady_clock::now() - start;
std::cout << "Crunching values on the CPU (serial): " << std::chrono::duration_cast<ms>(elapsed_cpu).count() / 1000.0 << "s" << std::endl;
int * pp;
cudaMalloc((void**)&pp, sizeof(int)); //initializing the device, to not affect the benchmark
fl_type *interp_value_gpu;
interp_value_gpu = (fl_type *)malloc(result_size* fl_size);
start = std::chrono::steady_clock::now();
cuda_interpolation_function(interp_value_gpu, result_size, grid_values, grid_values_size, weights, node_map, total_action_number, interp_dim, n_sim);
auto elapsed_gpu = std::chrono::steady_clock::now() - start;
std::cout << "Crunching values on the GPU: " << std::chrono::duration_cast<ms>(elapsed_gpu).count() / 1000.0 << "s" << std::endl;
float ms_cpu = std::chrono::duration_cast<ms>(elapsed_cpu).count();
float ms_gpu = std::chrono::duration_cast<ms>(elapsed_gpu).count();
int n_proc = 4;
std::cout << "Performance: " << (ms_gpu- ms_cpu / n_proc) / (ms_cpu / n_proc) * 100 << " % less time than parallel CPU!" << std::endl;
verify(interp_value_cpu, interp_value_gpu, result_size);
free(interp_value_cpu);
free(interp_value_gpu);
free(grid_values);
free(node_map);
free(weights);
}
void cuda_interpolation_function(fl_type* interp_value_gpu, int result_size, fl_type * grid_values, int grid_values_size, fl_type* weights, pos_type* node_map, int total_action_number, int interp_dim, int n_sim) {
int fl_size = sizeof(fl_type);
int pos_size = sizeof(pos_type);
auto start = std::chrono::steady_clock::now();
//device versions of the inputs
fl_type * grid_values_device;
fl_type* weights_device;
pos_type * node_map_device;
fl_type *interp_value_device;
int lenght_node_map = interp_dim*total_action_number;
std::cout << "size grid_values: " << grid_values_size <<std::endl;
std::cout << "size weights: " << lenght_node_map << std::endl;
std::cout << "size interp_value: " << result_size << std::endl;
//allocating and moving to the GPU the inputs
auto error_code=cudaMalloc((void**)&grid_values_device, grid_values_size*fl_size);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMalloc of the grid_values" << std::endl;
}
error_code=cudaMemcpy(grid_values_device, grid_values, grid_values_size*fl_size, cudaMemcpyHostToDevice);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMemcpy of the grid_values" << std::endl;
}
error_code=cudaMalloc((void**)&weights_device, lenght_node_map*fl_size);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMalloc of the weights" << std::endl;
}
error_code=cudaMemcpy(weights_device, weights, lenght_node_map*fl_size, cudaMemcpyHostToDevice);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMemcpy of the weights" << std::endl;
}
error_code=cudaMalloc((void**)&node_map_device, lenght_node_map*pos_size);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMalloc of node_map" << std::endl;
}
error_code=cudaMemcpy(node_map_device, node_map, lenght_node_map*pos_size, cudaMemcpyHostToDevice);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMemcpy of node_map" << std::endl;
}
error_code=cudaMalloc((void**)&interp_value_device, result_size*fl_size);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMalloc of interp_value_device " << std::endl;
}
auto elapsed_moving = std::chrono::steady_clock::now() - start;
float ms_moving = std::chrono::duration_cast<ms>(elapsed_moving).count();
cudaDeviceSynchronize();
//1d
int block_size = 1024;
int num_blocks = (result_size + block_size - 1) / block_size;
std::cout << "num_blocks:" << num_blocks << std::endl;
interp_kernel << < num_blocks, block_size >> > (interp_value_device, weights_device, node_map_device, grid_values_device, interp_dim, n_sim, total_action_number);
//2d
//int block_size2 = 32; //each block will have block_size2*block_size2 threads
//dim3 num_blocks2(block_size2, block_size2);
//int x_grid = (total_action_number + block_size2 - 1) / block_size2;
//int y_grid = (n_sim + block_size2 - 1) / block_size2;
//dim3 grid_size2(x_grid, y_grid);
//std::cout <<"grid:"<< x_grid<<" x "<< y_grid<<std::endl;
//interp_kernel2D <<< grid_size2, num_blocks2 >>> (interp_value_device, weights_device, node_map_device, grid_values_device, interp_dim, n_sim, total_action_number);
cudaDeviceSynchronize();
cudaError err = cudaGetLastError();
if (cudaSuccess != err)
{
std::cout << "Cuda kernel failed! " << cudaGetErrorString(err) <<std::endl;
}
start = std::chrono::steady_clock::now();
cudaMemcpy(interp_value_gpu, interp_value_device, result_size*fl_size, cudaMemcpyDeviceToHost);
auto elapsed_moving_back = std::chrono::steady_clock::now() - start;
float ms_moving_back = std::chrono::duration_cast<ms>(elapsed_moving_back).count();
std::cout << "Time spent moving the data to the GPU:" << ms_moving << " ms"<<std::endl;
std::cout << "Time spent moving the results back to the host: " << ms_moving_back << " ms" << std::endl;
cudaFree(interp_value_device);
cudaFree(weights_device);
cudaFree(node_map_device);
cudaFree(grid_values_device);
}
而且，我将非常感谢任何关于如何提高代码性能的指导。
2 个解决方案
解决方案1
1 已采纳 2017-07-30 14:55:41
任何时候你有麻烦了CUDA代码，我建议做适当的CUDA错误检查（你大多似乎在做）， 并运行你的代码的时间cuda-memcheck 。 最后一个实用程序与Nsight VSE中的“启用内存检查器”相似，但并不完全相同。 但是，Nsight VSE内存检查器可能已经给出了相同的指示。
在C（或C ++）中，数组的索引通常从0开始。因此，要测试越界索引，我必须检查生成的索引是否等于或大于数组的大小。 但是在您的情况下，您仅测试以下项目：
if (row > n_sim || column > num_cols) return;
您在1D内核和2D内核中都犯了类似的错误，尽管您认为1D内核可以正常工作，但实际上是在进行越界访问。 如果您使用上述的cuda-memcheck实用程序（或可能还可以使用可以在Nsight VSE中启用的内存检查器）运行，则可以验证这一点。
当我在pastebin链接中修改您的代码以使用正确的范围/边界检查时， cuda-memcheck报告没有错误，并且您的程序报告了正确的结果。 我已经测试了这两种情况，但是下面的代码已从您的pastebin链接修改为取消注释2D情况，并使用它代替了1D情况：
$ cat t375.cu | more
#include "cuda_runtime.h"
#include "device_launch_parameters.h"
#include <stdio.h>
#include <assert.h>
#include <iostream>
#include <random>
#include <chrono>
typedef float fl_type;
typedef int pos_type;
typedef std::chrono::milliseconds ms;
//declaration of the cuda function
void cuda_interpolation_function(fl_type* interp_value_back, int result_size, fl
_type * grid_values, int grid_values_size, fl_type* weights, pos_type* node_map,
int total_action_number, int interp_dim, int n_sim);
fl_type iterp_cpu(fl_type* weights, pos_type* node_map, fl_type* grid_values, in
t& row, int& column, int& interp_dim, int& n_sim) {
int w_p = column*interp_dim;
fl_type res = weights[w_p] * grid_values[row + node_map[w_p] * n_sim];
for (int inter_point = 1; inter_point < interp_dim; inter_point++) {
res += weights[w_p + inter_point] * grid_values[node_map[w_p + inter_poi
nt] * n_sim + row];
}
return res;
}
__global__ void interp_kernel(fl_type * d_matrix, fl_type* weights, pos_type* no
de_map, fl_type* grid_values, int interp_dim, int n_sim, int num_cols) {
int index = blockIdx.x * blockDim.x + threadIdx.x;
int column = index / n_sim;
int row = index % n_sim;
int w_p = column*interp_dim;
if (row >= n_sim || column >= num_cols) return; // modified
fl_type res = weights[w_p] * grid_values[row + node_map[w_p] * n_sim];
for (int inter_point = 1; inter_point < interp_dim; inter_point++) {
res += weights[w_p + inter_point] * grid_values[row + node_map[w_p + int
er_point] * n_sim];
}
d_matrix[index] = res;
}
__global__ void interp_kernel2D(fl_type * d_matrix, fl_type* weights, pos_type*
node_map, fl_type* grid_values, int interp_dim, int n_sim, int num_cols) {
int column = blockIdx.x * blockDim.x + threadIdx.x;
int row = blockIdx.y * blockDim.y + threadIdx.y;
int index = column*n_sim + row;
int w_p = column*interp_dim;
if (row >= n_sim || column >= num_cols) return; // modified
fl_type res = weights[w_p] * grid_values[row + node_map[w_p] * n_sim];
for (int inter_point = 1; inter_point < interp_dim; inter_point++) {
res += weights[w_p + inter_point] * grid_values[row + node_map[w_p + int
er_point] * n_sim];
}
d_matrix[index] = res;
}
void verify(fl_type *host, fl_type *device, int size) {
int count = 0;
int count_zero = 0;
for (int i = 0; i < size; i++) {
if (host[i] != device[i]) {
count++;
//std::cout <<"pos: " <<i<< " CPU:" <<h[i] << ", GPU: " << d[
i] <<std::endl;
assert(host[i] == device[i]);
if (device[i] == 0.0)
count_zero++;
}
}
if (count) {
std::cout << "Non matching: " << count << "out of " << size << "(" << (f
loat(count) / size * 100) << "%)" << std::endl;
std::cout << "Zeros returned from the device: " << count_zero <<"(" << (
float(count_zero) / size * 100) << "%)" << std::endl;
}
else
std::cout << "Perfect match!" << std::endl;
}
int main() {
int fl_size = sizeof(fl_type);
int pos_size = sizeof(pos_type);
int dim = 5; // range: 2-5
int number_nodes = 5500; // range: 10.000-500.000
int max_actions = 12; // range: 6-200
int n_sim = 1000; // range: 1.000-10.000
int interp_dim = std::pow(2, dim);
int grid_values_size = n_sim*number_nodes;
std::default_random_engine generator;
std::normal_distribution<fl_type> normal_dist(0.0, 1);
std::uniform_int_distribution<> uniform_dist(0, number_nodes - 1);
double bit_allocated = 0;
fl_type * grid_values; //flattened 2d array, containing the value of the grid (n_sims x number_nodes)
grid_values = (fl_type *)malloc(grid_values_size * fl_size);
bit_allocated += grid_values_size * fl_size;
for (int i = 0; i < grid_values_size; i++)
grid_values[i] = normal_dist(generator);
pos_type * map_node2values_start; //vector that maps each node to the first column of the result matrix regarding that done
pos_type * map_node2values_how_many; //vector that stores how many action we have per node
map_node2values_start = (pos_type *)malloc(number_nodes * pos_size);
map_node2values_how_many = (pos_type *)malloc(number_nodes * pos_size);
bit_allocated += 2 * (number_nodes * pos_size);
for (int i = 0; i < number_nodes; i++) {
//each node as simply max_actions
map_node2values_start[i] = max_actions*i;
map_node2values_how_many[i] = max_actions;
}
//total number of actions, which is amount of column of the results
int total_action_number = map_node2values_start[number_nodes - 1] + map_node2values_how_many[number_nodes - 1];
//vector that keep tracks of the columnt to grab, and their weight in the interpolation
fl_type* weights;
pos_type * node_map;
weights = (fl_type *)malloc(total_action_number*interp_dim * pos_size);
bit_allocated += total_action_number * fl_size;
node_map = (pos_type *)malloc(total_action_number*interp_dim * pos_size);
bit_allocated += total_action_number * pos_size;
//filling with random numbers
for (int i = 0; i < total_action_number*interp_dim; i++) {
node_map[i] = uniform_dist(generator); // picking random column
weights[i] = 1.0 / interp_dim; // uniform weights
}
std::cout << "done filling!" << std::endl;
std::cout << bit_allocated / 8 / 1024 / 1024 << "MB allocated" << std::endl;
int result_size = n_sim*total_action_number;
fl_type *interp_value_cpu;
bit_allocated += result_size* fl_size;
interp_value_cpu = (fl_type *)malloc(result_size* fl_size);
auto start = std::chrono::steady_clock::now();
for (int row = 0; row < n_sim; row++) {
for (int column = 0; column < total_action_number; column++) {
auto zz = iterp_cpu(weights, node_map, grid_values, row, column, interp_dim, n_sim);
interp_value_cpu[column*n_sim + row] = zz;
}
}
auto elapsed_cpu = std::chrono::steady_clock::now() - start;
std::cout << "Crunching values on the CPU (serial): " << std::chrono::duration_cast<ms>(elapsed_cpu).count() / 1000.0 << "s" << std::endl;
int * pp;
cudaMalloc((void**)&pp, sizeof(int)); //initializing the device, to not affect the benchmark
fl_type *interp_value_gpu;
interp_value_gpu = (fl_type *)malloc(result_size* fl_size);
start = std::chrono::steady_clock::now();
cuda_interpolation_function(interp_value_gpu, result_size, grid_values, grid_values_size, weights, node_map, total_action_number, interp_dim, n_sim);
auto elapsed_gpu = std::chrono::steady_clock::now() - start;
std::cout << "Crunching values on the GPU: " << std::chrono::duration_cast<ms>(elapsed_gpu).count() / 1000.0 << "s" << std::endl;
float ms_cpu = std::chrono::duration_cast<ms>(elapsed_cpu).count();
float ms_gpu = std::chrono::duration_cast<ms>(elapsed_gpu).count();
int n_proc = 4;
std::cout << "Performance: " << (ms_gpu- ms_cpu / n_proc) / (ms_cpu / n_proc) * 100 << " % less time than parallel CPU!" << std::endl;
verify(interp_value_cpu, interp_value_gpu, result_size);
free(interp_value_cpu);
free(interp_value_gpu);
free(grid_values);
free(node_map);
free(weights);
}
void cuda_interpolation_function(fl_type* interp_value_gpu, int result_size, fl_type * grid_values, int grid_values_size, fl_type* weights, pos_type* node_map, int total_action_number, int interp_dim, int n_sim) {
int fl_size = sizeof(fl_type);
int pos_size = sizeof(pos_type);
auto start = std::chrono::steady_clock::now();
//device versions of the inputs
fl_type * grid_values_device;
fl_type* weights_device;
pos_type * node_map_device;
fl_type *interp_value_device;
int lenght_node_map = interp_dim*total_action_number;
std::cout << "size grid_values: " << grid_values_size <<std::endl;
std::cout << "size weights: " << lenght_node_map << std::endl;
std::cout << "size interp_value: " << result_size << std::endl;
//allocating and moving to the GPU the inputs
auto error_code=cudaMalloc((void**)&grid_values_device, grid_values_size*fl_size);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMalloc of the grid_values" << std::endl;
}
error_code=cudaMemcpy(grid_values_device, grid_values, grid_values_size*fl_size, cudaMemcpyHostToDevice);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMemcpy of the grid_values" << std::endl;
}
error_code=cudaMalloc((void**)&weights_device, lenght_node_map*fl_size);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMalloc of the weights" << std::endl;
}
error_code=cudaMemcpy(weights_device, weights, lenght_node_map*fl_size, cudaMemcpyHostToDevice);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMemcpy of the weights" << std::endl;
}
error_code=cudaMalloc((void**)&node_map_device, lenght_node_map*pos_size);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMalloc of node_map" << std::endl;
}
error_code=cudaMemcpy(node_map_device, node_map, lenght_node_map*pos_size, cudaMemcpyHostToDevice);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMemcpy of node_map" << std::endl;
}
error_code=cudaMalloc((void**)&interp_value_device, result_size*fl_size);
if (error_code != cudaSuccess) {
std::cout << "Error during cudaMalloc of interp_value_device " << std::endl;
}
auto elapsed_moving = std::chrono::steady_clock::now() - start;
float ms_moving = std::chrono::duration_cast<ms>(elapsed_moving).count();
cudaDeviceSynchronize();
//1d
#if 0
int block_size = 1024;
int num_blocks = (result_size + block_size - 1) / block_size;
std::cout << "num_blocks:" << num_blocks << std::endl;
interp_kernel << < num_blocks, block_size >> > (interp_value_device, weights_device, node_map_device, grid_values_device, interp_dim, n_sim, total_action_number);
#endif
//2d
int block_size2 = 32; //each block will have block_size2*block_size2 threads
dim3 num_blocks2(block_size2, block_size2);
int x_grid = (total_action_number + block_size2 - 1) / block_size2;
int y_grid = (n_sim + block_size2 - 1) / block_size2;
dim3 grid_size2(x_grid, y_grid);
std::cout <<"grid:"<< x_grid<<" x "<< y_grid<<std::endl;
interp_kernel2D <<< grid_size2, num_blocks2 >>> (interp_value_device, weights_device, node_map_device, grid_values_device, interp_dim, n_sim, total_action_number);
cudaDeviceSynchronize();
cudaError err = cudaGetLastError();
if (cudaSuccess != err)
{
std::cout << "Cuda kernel failed! " << cudaGetErrorString(err) <<std::endl;
}
start = std::chrono::steady_clock::now();
cudaMemcpy(interp_value_gpu, interp_value_device, result_size*fl_size, cudaMemcpyDeviceToHost);
auto elapsed_moving_back = std::chrono::steady_clock::now() - start;
float ms_moving_back = std::chrono::duration_cast<ms>(elapsed_moving_back).count();
std::cout << "Time spent moving the data to the GPU:" << ms_moving << " ms"<<std::endl;
std::cout << "Time spent moving the results back to the host: " << ms_moving_back << " ms" << std::endl;
cudaFree(interp_value_device);
cudaFree(weights_device);
cudaFree(node_map_device);
cudaFree(grid_values_device);
}
$ nvcc -arch=sm_52 -o t375 t375.cu -std=c++11
$ cuda-memcheck ./t375
========= CUDA-MEMCHECK
done filling!
2.69079MB allocated
Crunching values on the CPU (serial): 30.081s
size grid_values: 5500000
size weights: 2112000
size interp_value: 66000000
grid:2063 x 32
Time spent moving the data to the GPU:31 ms
Time spent moving the results back to the host: 335 ms
Crunching values on the GPU: 7.089s
Performance: -5.73452 % less time than parallel CPU!
Perfect match!
========= ERROR SUMMARY: 0 errors
$
请注意， cuda-memcheck会减慢您的程序在GPU上的执行速度，以进行严格的内存边界检查。 因此，性能可能与普通情况不符。 这是“常规”运行的样子：
$ ./t375
done filling!
2.69079MB allocated
Crunching values on the CPU (serial): 30.273s
size grid_values: 5500000
size weights: 2112000
size interp_value: 66000000
grid:2063 x 32
Time spent moving the data to the GPU:32 ms
Time spent moving the results back to the host: 332 ms
Crunching values on the GPU: 1.161s
Performance: -84.6596 % less time than parallel CPU!
Perfect match!
$
解决方案2
1
您正在访问分配的块之外的内存。 要检查行索引和列索引是否在范围内：
if (row >= n_rows || column >= num_cols) return; // Do this
if (row > n_rows || column > num_cols) return; // Instead of this
在平面版本中，此int row = index % n_rows; 使row保持在n_rows以下。 您只能访问已分配内存之外的一列，对于较小的矩阵，该列可能仍与内存对齐有关。 Python演示 。
第二个版本确实访问了一个额外的列plus和extra元素， 以及每行一个额外的元素（下一行的第一个元素），如下所示：
int row = blockIdx.y * blockDim.y + threadIdx.y;
行索引不再保持在有效范围内。 Python演示 。
查看您的pastebin，可能是它破裂的地方：
44. fl_type res = weights[w_p] * grid_values[row + node_map[w_p] * n_sim];
^^^
45. for (int inter_point = 1; inter_point < interp_dim; inter_point++) {
46. res += weights[w_p + inter_point] * \
grid_values[row + node_map[w_p + inter_point] * n_sim];
^^^
47. }
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