Matlab Cuda块和线程ID

Question

我在使用Matlab和CUDA时遇到了一些奇怪的问题。基本上，我有这个CUDA代码打印以下

1. 本地主题ID
2. 本地区块ID
3. 本地块尺寸
4. 全局主题ID

CUDA代码

#include "cuda_runtime.h
#include "device_launch_parameters.h"
#include <stdio.h>

//device functions
 __device__ int getGlobalidx_1d_1d()

{
    return blockIdx.x *blockDim.x + threadIdx.x;
}

//kernels
__global__ void kernel_1D_1D()
{
    printf("Local thread ID: %i  Local Block ID: %i, Local Block Dim: %i, Global Thread ID: %i\n", threadIdx.x, blockIdx.x, blockDim.x, getGlobalIdx_1D_1D());

}

int main()
{
printf("\nLaunching kernel as 1D grid of 1D blocks...\n");
kernel_1D_1D<<<dim3(2,1,1), dim3(10,1,1)>>>();
cudaDeviceReset();

return 0;
}

这一切都很好，很好

http://postimg.org/image/4tllso2tx/

然而，当我在Matlab中做同样的事情时，事情变得棘手

我应该得到一个矩阵，

1. 阻止0-1
2. 主题0-9
3. 全球识别号0-19
4. 阻挡昏暗10对

换句话说

• 0 .... 0 .... 0 ...... 0 ...... 1 .... .... 1 1 ...... 1
• 0 .... .... 1 2 ...... 9 ...... 0 .... .... 1 2 ...... 9
• 0 .... .... 1 2 ...... 9 ...... 10..11..12 .... 19
• 10..10..10 .... 10 .... 10..10..10 .... 10

相反，当我提供带有参数2和10的Matlab函数时，值就到处都是

http://postimg.org/image/haiii0cjt/

Matlab功能代码

function[returnValues] = Blocks_Threads_Test(blocks,threads)

%1  Create Cuda Kernel Object

k = parallel.gpu.CUDAKernel('BlocksThreads.ptx', 'BlocksThreads.cu','BlocksThreads');

%2 Set Object properties

k.GridSize = [blocks];
k.ThreadBlockSize = [threads];

%3 Set Argument Variables

gpu_Values = gpuArray(ones(4,blocks*threads));

[data] = feval(k, gpu_Values);


returnValues = gather(data);

Cuda Matlab代码

#include "cuda_runtime.h"
#include "device_launch_parameters.h"
#include <stdio.h>

__global__ void BlocksThreads(double *values) 
{
    unsigned int bx = blockIdx.x;
    unsigned int tx = threadIdx.x;
    unsigned long int globalID = (bx*blockDim.x) + tx;


    values[(bx*blockDim.x) + (tx*4) + 0] = bx; //Block Number
    values[(bx*blockDim.x) + (tx*4) + 1] = tx; //Thread Number
    values[(bx*blockDim.x) + (tx*4) + 2] = globalID; 
    values[(bx*blockDim.x) + (tx*4) + 3] = blockDim.x; //Threads/Block
}

有谁知道为什么matlab中的线程，块和全局变量的id值都到位了？更不用说Matrix甚至没有填写整个过程。

如果相关，这就是我正在运行的

• Win 7 64
• VS 2012
• Matlab 2013b 64
• Nvidia GeForce GTX 770
• Compute 3.0

Answer 1

您对values矩阵的索引编号错误。变化

values[(bx*blockDim.x) + (tx*4) + k] with k=0,1,2,3

到

values[4*globalID + k] with k=0,1,2,3