everyone:
Recently I have tried to utilize the most recent property of cuda 5.5 to program, i.e., dynamic parallelism. But I have some very confusing problem. My code is here:
/* Includes, system */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <iostream>
using namespace std;
/* Includes, cuda */
#include <cuda_runtime.h>
#include <cublas_v2.h>
/* Includes, cuda helper functions */
#include <helper_cuda.h>
#include "kernels.cu"
/* Matrix size */
#define N (275)
#define LengthSignal (64)
#define AmountSignal (255025)
#define NBLOCKX (32768)
#define NTHREADS_PER_BLOCK (128)
/* Declaration of the function that computes sgemm using CUBLAS device API */
__global__ void invokeDeviceCublasSgemm(float *d_A, float *Test);
/* Main */
int main(int argc, char **argv)
{
float *h_A;
float *d_A = 0;
int n2 = N * N;
h_A = (float *)malloc(n2 * sizeof(h_A[0]));
/* Fill the matrices with test data */
for (int i = 0; i < n2; i++)
{
h_A[i] = rand() / (float)RAND_MAX;
}
cudaMalloc((void **)&d_A, n2 * sizeof(h_A[0]));
/* Initialize the device matrices with the host matrices */
// cudaMemcpy(d_A, h_A, sizeof(float) * LengthSignal * AmountSignal, cudaMemcpyHostToDevice);
cudaMemcpy(d_A, h_A, n2 * sizeof(h_A[0]), cudaMemcpyHostToDevice);
int Length = 100;
float *h_Test = (float *) malloc(sizeof(float) * Length);
float *d_Test;
cudaMalloc((void **) &d_Test, sizeof(float) * Length);
cudaMemset(d_Test, 0, sizeof(float) * Length);
invokeDeviceCublasSgemm<<<NBLOCKX, NTHREADS_PER_BLOCK>>>(d_A, d_Test);
cudaMemcpy(h_Test, d_Test, sizeof(float) * Length, cudaMemcpyDeviceToHost);
printf("\n The first 10 elements of d_A in location 1 are: \n");
for (int j = 0; j < 10; j ++)
{
printf("%f ", h_Test[j]);
}
printf("\n The first 10 elements of d_A in location 2 are: \n");
for (int j = 10; j < 20; j ++)
{
printf("%f ", h_Test[j]);
}
printf("\n");
free(h_Test);
cudaFree(d_Test);
/* Memory clean up */
free(h_A);
cudaFree(d_A);
}
#ifndef __GLOBAL__CU__
#define __GLOBAL__CU__
__global__ void invokeDeviceCublasSgemm(float *d_A, float *Test)
{
// save the first 10 elements of d_A in location 1
for (int j = 0; j < 10; j ++)
{
Test[j] = d_A[j];
}
cublasHandle_t cnpHandle;
cublasCreate(&cnpHandle);
// save the first 10 elements of d_A in location 2
for (int j = 10; j < 20; j ++)
{
Test[j] = d_A[j - 10];
}
cublasDestroy(cnpHandle);
}
#endif
If I set the configuration parameters as <<<1, 1>>>, everything works well. And the output is like that:
The first 10 elements of d_A in location 1 are:
0.840188 0.394383 0.783099 0.798440 0.911647 0.197551 0.335223 0.768230 0.277775 0.553970
The first 10 elements of d_A in location 2 are:
0.840188 0.394383 0.783099 0.798440 0.911647 0.197551 0.335223 0.768230 0.277775 0.553970
However, if I set the configuration parameters as <<<32768, 128>>>, the output is quite weird. And the output is like that:
The first 10 elements of d_A in location 1 are:
-0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
The first 10 elements of d_A in location 2 are:
0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000 0.000000
I really don't know why! My code is just come from the "samples" with a little change.
And then I just delete the last code "cublasDestroy(cnpHandle);", then it becomes normal. And the output is:
The first 10 elements of d_A in location 1 are:
0.840188 0.394383 0.783099 0.798440 0.911647 0.197551 0.335223 0.768230 0.277775 0.553970
The first 10 elements of d_A in location 2 are:
0.840188 0.394383 0.783099 0.798440 0.911647 0.197551 0.335223 0.768230 0.277775 0.553970
Did someone have the same problem?
Thanks!