Results 1 to 2 of 2

Thread: dot product of two vectors using reduction

  1. #1

    dot product of two vectors using reduction

    #include <stdio.h>
    #include <stdlib.h>

    #ifdef __APPLE__
    #include <OpenCL/opencl.h>
    #else
    #include <CL/cl.h>
    #endif

    #define MAX_SOURCE_SIZE (0x100000)

    int main(void) {
    // Create the two input vectors
    int i;


    int LIST_SIZE = 8;//declaring the size
    int *A = (int*)malloc(sizeof(int)*LIST_SIZE); // Allocating the memory for set A
    int *B = (int*)malloc(sizeof(int)*LIST_SIZE); // Allocating the memory for set A

    printf("getting the first set\n");
    for(i = 0; i < LIST_SIZE; i++)
    {
    A[i] = i;B[i] = i*2;
    printf("A[%d]=%d \t B[%d]=%d\n",i,A[i],i,B[i]);

    }




    // Load the kernel source code into the array source_str
    FILE *fp;
    char *source_str;
    size_t source_size;

    fp = fopen("new_kernel.cl", "r");
    if (!fp) {
    fprintf(stderr, "Failed to load kernel.\n");
    exit(1);
    }
    source_str = (char*)malloc(MAX_SOURCE_SIZE);
    source_size = fread( source_str, 1, MAX_SOURCE_SIZE, fp);
    fclose( fp );

    // Get platform and device information
    cl_platform_id platform_id = NULL;
    cl_device_id device_id = NULL;
    cl_uint ret_num_devices;
    cl_uint ret_num_platforms;
    cl_int ret = clGetPlatformIDs(1, &platform_id, &ret_num_platforms);
    ret = clGetDeviceIDs( platform_id, CL_DEVICE_TYPE_ALL, 1,
    &device_id, &ret_num_devices);

    // Create an OpenCL context
    cl_context context = clCreateContext( NULL, 1, &device_id, NULL, NULL, &ret);

    // Create a command queue
    cl_command_queue command_queue = clCreateCommandQueue(context, device_id, 0, &ret);

    // Create memory buffers on the device for each vector
    cl_mem a_mem_obj = clCreateBuffer(context, CL_MEM_READ_ONLY, LIST_SIZE * sizeof(int), NULL, &ret);
    cl_mem b_mem_obj = clCreateBuffer(context, CL_MEM_READ_ONLY, LIST_SIZE * sizeof(int), NULL, &ret);
    cl_mem c_mem_obj = clCreateBuffer(context, CL_MEM_READ_WRITE,LIST_SIZE * sizeof(int), NULL, &ret);

    // Copy the lists A and B to their respective memory buffers
    ret = clEnqueueWriteBuffer(command_queue, a_mem_obj, CL_TRUE, 0, LIST_SIZE * sizeof(int), A, 0, NULL, NULL);
    ret = clEnqueueWriteBuffer(command_queue, b_mem_obj, CL_TRUE, 0, LIST_SIZE * sizeof(int), B, 0, NULL, NULL);

    // Create a program from the kernel source
    cl_program program = clCreateProgramWithSource(context, 1,
    (const char **)&source_str, (const size_t *)&source_size, &ret);

    // Build the program
    ret = clBuildProgram(program, 1, &device_id, NULL, NULL, NULL);

    // Create the OpenCL kernel
    cl_kernel kernel = clCreateKernel(program, "new", &ret);

    // Set the arguments of the kernel
    ret = clSetKernelArg(kernel, 0, sizeof(cl_mem), (void *)&a_mem_obj);
    ret = clSetKernelArg(kernel, 1, sizeof(cl_mem), (void *)&b_mem_obj);
    ret = clSetKernelArg(kernel, 2, sizeof(cl_mem), (void *)&c_mem_obj);
    ret = clSetKernelArg(kernel, 3, sizeof(cl_int), NULL);//local prods array
    ret = clSetKernelArg(kernel, 4, sizeof(cl_int), (void *)&LIST_SIZE);


    // Execute the OpenCL kernel on the list
    size_t global_item_size = LIST_SIZE; // Process the entire lists
    size_t local_item_size = 2; // Process in groups of 64
    ret = clEnqueueNDRangeKernel(command_queue, kernel, 1, NULL,
    &global_item_size, &local_item_size, 0, NULL, NULL);

    // Read the memory buffer C on the device to the local variable C
    int *C = (int*)malloc(sizeof(int)*LIST_SIZE);
    ret = clEnqueueReadBuffer(command_queue, c_mem_obj, CL_TRUE, 0,
    LIST_SIZE * sizeof(int), C, 0, NULL, NULL);

    // Display the result to the screen

    int val=0;

    for(i = 0; i < 2; i++)
    {
    val=val+C[i];
    }
    printf("value is %d\n",val);
    // Clean up
    ret = clFlush(command_queue);
    ret = clFinish(command_queue);
    ret = clReleaseKernel(kernel);
    ret = clReleaseProgram(program);
    ret = clReleaseMemObject(a_mem_obj);
    ret = clReleaseMemObject(a_mem_obj);
    ret = clReleaseMemObject(c_mem_obj);
    ret = clReleaseCommandQueue(command_queue);
    ret = clReleaseContext(context);
    free(A);
    free(B);
    free(C);
    return 0;
    }

    kernel function:

    _kernel void new(__global int* A, __global int *C, __local int* cache, int LIST_SIZE){
    int tid = get_global_id(0);
    int cacheIndex = get_local_id(0);
    int blockDim.x = get_local_size(0);
    int blockIdx.x = get_group_id(0);
    int gridDim.x = get_num_groups(0);

    int temp=0;
    while(tid<N)
    {
    temp+=a[tid] * b[tid];
    tid+= blockDim.x * gridDim.x;
    }
    cache[cacheIndex] = temp;
    barrier(CLK_LOCAL_MEM_FENCE);
    int i= blockDim.x/2;
    while(i!=0)
    {
    if(cacheIndex < i)
    cache[cacheIndex] += cache[cacheIndex + i];
    barrier(CLK_GLOBAL_MEM_FENCE);
    i/=2;
    }
    if(cacheIndex == 0)
    C[blockIdx.x] = cache[0];

    }

    Error:etting the first set
    A[0]=0 B[0]=0
    A[1]=1 B[1]=2
    A[2]=2 B[2]=4
    A[3]=3 B[3]=6
    A[4]=4 B[4]=8
    A[5]=5 B[5]=10
    A[6]=6 B[6]=12
    A[7]=7 B[7]=14
    value is 902153097
    Segmentation fault (core dumped)

    can you tell me the error

  2. #2
    Senior Member
    Join Date
    Oct 2012
    Posts
    112

    Re: dot product of two vectors using reduction

    clSetKernelArg(kernel, 3, sizeof(cl_int), NULL) declares the local buffer with a size of sizeof(cl_int) (4 bytes), which is not enough to store more than one integer...

Similar Threads

  1. dot product
    By mustang in forum OpenCL
    Replies: 6
    Last Post: 03-07-2012, 04:53 AM
  2. Array reduction example
    By toastedcrumpets in forum OpenCL
    Replies: 1
    Last Post: 11-05-2009, 06:02 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •