OpenCl中的共享内存

Shared memory in OpenCL

本文关键字:内存 共享 OpenCl      更新时间:2023-10-16

i打算执行向量操作,并尝试使用添加矢量和乘法的小虚拟程序。但是,由于我对共享内存的知识的限制,该代码不会运行。Internet中的所有来源都显示2D矩阵操作,我无法将其转换为矢量问题。考虑到我是Opencl的新手,请尝试解释我要在哪里出错。代码如下:

主机代码:

std::vector<cl::Platform> platforms;
std::vector<cl::Device> devices;
cl::Context context;
cl::CommandQueue queue;
cl::Program program;
cl::Kernel kernel;
cl::Platform::get(&platforms);
deviceUsed = 0;
cl_context_properties properties[] =
{ CL_CONTEXT_PLATFORM, (cl_context_properties)(platforms[0])(),0 };
context = cl::Context(CL_DEVICE_TYPE_ALL, properties);
devices = context.getInfo<CL_CONTEXT_DEVICES>();
queue = cl::CommandQueue(context, devices[deviceUsed]);
cl::Program::Sources source( 1, std::make_pair(kernel_source.c_str(),  kernel_source.size()));
program = cl::Program(context, source);
program.build(devices);
std::vector < float > a;
std::vector < float > b;
std::vector < float > sum;
std::vector < float > prod;
int globalSize = 128;
int localSize = 16;
a.resize(globalSize);
b.resize(globalSize);
sum.resize(globalSize);
prod.resize(globalSize);
for (int i = 0; i < globalSize ; i++)
{
    a[i] = 1.0f * i;
    b[i] = 5.0f * i;
}
cl::Buffer buffer_A;
cl::Buffer buffer_B;
cl::Buffer buffer_sum;
cl::Buffer buffer_prod;
buffer_A = cl::Buffer (context, CL_MEM_READ_WRITE, sizeof(float) * globalSize);
buffer_B = cl::Buffer (context, CL_MEM_READ_WRITE, sizeof(float) * globalSize);
queue.enqueueWriteBuffer(buffer_A, CL_TRUE, 0, sizeof(float) * globalSize , &a[0]);
queue.enqueueWriteBuffer(buffer_B, CL_TRUE, 0, sizeof(float) * globalSize , &b[0]);
buffer_sum = cl::Buffer(context, CL_MEM_WRITE_ONLY, sizeof(float) * globalSize);
buffer_prod = cl::Buffer(context, CL_MEM_WRITE_ONLY, sizeof(float) * globalSize);
kernel.setArg(0, buffer_A);
kernel.setArg(1, buffer_B);
kernel.setArg(2, buffer_sum);
kernel.setArg(3, buffer_prod);
queue.enqueueNDRangeKernel(kernel, cl::NullRange, cl::NDRange(globalSize/localSize), cl::NDRange(N), NULL);
queue.finish();
queue.enqueueReadBuffer(buffer_sum, CL_TRUE, 0, sizeof(float) * globalSize, &sum[0]);
queue.enqueueReadBuffer(buffer_prod, CL_TRUE, 0, sizeof(float) * globalSize, &prod[0]);

内核:

#define STRINGI(ker) #ker
std::string kernel_source = STRINGI(
__kernel void KernelAddMul(__global float* a, __global float* b, __global float* sum, __global float* prod)
{
    unsigned int j = get_local_id(0);
    int N = get_local_size(0);
    unsigned int i = N * get_global_id(0) + j;
    float locSum[N];
    float locProd[N];
    __local float Asub[N];
    __local float Bsub[N];
    for(int k = 0; k < N; k++){
        Asub[k] = a[i];
        Bsub[k] = b[i];
        barrier(CLK_LOCAL_MEM_FENCE);
        locSum[k] = Asub[k] + Bsub[k];
        locProd[k] = Asub[k] * Bsub[k];
        barrier(CLK_LOCAL_MEM_FENCE);
        sum[i] = locSum[k];
        prod[i] = locProd[k];
     }
} 
);

我怀疑您的代码不运行,因为您的内核没有编译。

以下行无效:

int N = get_local_size(0);
float locSum[N];
float locProd[N];
__local float Asub[N];
__local float Bsub[N];

N必须是一个常数,您不能使用get_local_size(0)动态大小数组。

我强烈建议您使用独立编译器来编译内核:codexl非常好,英特尔也是如此SDK用于OpenCl。一切都比尝试在应用程序中调试内核更好!