Hi everyone,
I’m trying for the first time to use #cufft using #openacc. I reproduce my problem with the following simple example. I have as an input an array of 10 real elements (a) initialized with 1, and the output (b) is supposed to be its Fourier transform (b should be zeros except for b[0] = 10 ).
But I encounter a runtime error at the line where cufftPlan1d is called (please see the code below). However, when CHECK_CUFFT macro is not used, the program is executed, but with wrong values of b[i] = 0, i = 0, ..., 9., in fact, they are simply the initial values of b.
I would ask two questions:
1- What is the mistake I made that prevent me from getting the correct answer?
2- How to print out the runtime error, or make some additional diagnostic that allows me to figure out this type of error?
I compiled the code with as follows
#!/bin/bash
compileNV=/opt/nvidia/hpc_sdk/Linux_x86_64/2023/compilers/bin/nvc++
#FLAGS="-O2 -g -gopt -Kieee -Minfo=accel -acc=noautoptr,sync,gpu -gpu=cc75,cuda10.2,lineinfo,ptxinfo -cudalib=curand"
FLAGS="-O2 -lm -lcufft -march=native -g -gopt -Kieee -Minfo=accel -acc=noautopar,sync,gpu -gpu=cc75,cuda12.0,lineinfo,ptxinfo -cudalib=curand"
#export NVCOMPILER_ACC_NOTIFY=3
$compileNV -o 1DFFT_GPU example1DFFT_GPU.cpp $FLAGS
Here is the source code:
/* Example of the problem : example1DFFT_GPU.cpp */
#include <iostream>
#include <vector>
#include <cmath>
#include <complex>
#include "openacc.h"
#include <cuda_runtime.h>
#include <cufftXt.h>
#include "../common.h"
int main()
{
const int m = 10;
std::complex<float> a[m];
std::complex<float> b[m];
cufftHandle plan1D;
for(unsigned int i = 0; i < m; i++)
{
a[i] = 1.0;
}
for(unsigned int i = 0; i < m; i++)
{
std::cout << a[i].real() << " , " << a[i].imag() << "\n";
}
#pragma acc data copyin(a[0 : m]) copyout(b[0 : m])
{
CHECK_CUFFT(cufftPlan1d(&plan1D, m, CUFFT_C2C, 1));
CHECK_CUFFT(cufftSetStream(plan1D, (cudaStream_t) acc_get_cuda_stream(acc_async_sync)));
#pragma acc host_data use_device(a, b)
{
CHECK_CUFFT(cufftExecC2C( plan1D,
(cufftComplex *) a,
(cufftComplex *) b,
CUFFT_FORWARD));
}
}
for(unsigned int i = 0; i < m; i++)
{
std::cout << b[i].real() << " , " << b[i].imag() << "\n";
}
CHECK_CUFFT(cufftDestroy(plan1D));
return 0;
}
Her is the common.h file
/* common.h file */
#include <sys/time.h>
/**
* @brief This piece of code is copied from
*
* https://github.com/deeperlearning/professional-cuda-c-programming/blob/master/examples/common/common.h
*
*/
#ifndef _COMMON_H
#define _COMMON_H
#define CHECK(call) \
{ \
const cudaError_t error = call; \
if (error != cudaSuccess) \
{ \
fprintf(stderr, "Error: %s:%d, ", __FILE__, __LINE__); \
fprintf(stderr, "code: %d, reason: %s\n", error, \
cudaGetErrorString(error)); \
} \
}
#define CHECK_CUFFT(call) \
{ \
cufftResult err; \
if ( (err = (call)) != CUFFT_SUCCESS) \
{ \
fprintf(stderr, "Got CUFFT error %d at %s:%d\n", err, __FILE__, \
__LINE__); \
exit(1); \
} \
}
#endif // _COMMON_H
thanks for your help