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#include <fftw3.h> | |
#include <chrono> | |
#include <iostream> | |
#include <omp.h> | |
#include <vector> | |
int main(int argc, char ** argv){ | |
using namespace std::chrono; | |
fftwf_complex *in, *out; | |
size_t n1 = 256; | |
size_t n2 = 256; | |
size_t n3 = 64; | |
size_t tot = n1*n2*n3; | |
size_t repeats = 1000; | |
in = (fftwf_complex*) fftw_malloc(sizeof(fftwf_complex)*tot); | |
out = (fftwf_complex*) fftw_malloc(sizeof(fftwf_complex)*tot); | |
const int n[2] = {n1,n2}; | |
auto start1 = system_clock::now(); | |
for (size_t i = 0; i < repeats; i++){ | |
auto p_standard = fftwf_plan_dft_2d(n1,n2,in,out,FFTW_FORWARD,FFTW_ESTIMATE); | |
#pragma omp parallel for | |
for (size_t k = 0; k < n3; k++){ | |
fftwf_execute_dft(p_standard,in+n1*n2*k,out+n1*n2*k); | |
} | |
} | |
auto end1 = system_clock::now(); | |
std::cout << "OMP loop (warmup): " << duration_cast<milliseconds>(end1-start1).count() << std::endl; | |
start1 = system_clock::now(); | |
for (size_t i = 0; i < repeats; i++){ | |
auto p_standard = fftwf_plan_dft_2d(n1,n2,in,out,FFTW_FORWARD,FFTW_ESTIMATE); | |
#pragma omp parallel for | |
for (size_t k = 0; k < n3; k++){ | |
fftwf_execute_dft(p_standard,in+n1*n2*k,out+n1*n2*k); | |
} | |
} | |
end1 = system_clock::now(); | |
std::cout << "OMP loop (second run): " << duration_cast<milliseconds>(end1-start1).count() << std::endl; | |
fftwf_init_threads(); | |
fftwf_plan_with_nthreads(omp_get_max_threads()); | |
auto start = system_clock::now(); | |
for (size_t i = 0; i < repeats; i++) { | |
auto p = fftwf_plan_many_dft(2,n,n3,in,n,1,n1*n2,out,n,1,n1*n2,FFTW_FORWARD,FFTW_ESTIMATE); | |
fftwf_execute(p); | |
} | |
auto end = system_clock::now(); | |
std::cout << "Naive: " << duration_cast<milliseconds>(end-start).count() << std::endl; | |
start = system_clock::now(); | |
for (size_t i=0; i < repeats; i++){ | |
auto p = fftwf_plan_many_dft(2,n,n3,in,n,1,n1*n2,in,n,1,n1*n2,FFTW_FORWARD,FFTW_ESTIMATE); | |
fftwf_execute(p); | |
} | |
end = system_clock::now(); | |
std::cout << "In place: " << duration_cast<milliseconds>(end-start).count() << std::endl; | |
start = system_clock::now(); | |
for (size_t i = 0; i < repeats; i++){ | |
auto p = fftwf_plan_many_dft(2,n,n3,in,n,1,n1*n2,out,n,1,n1*n2,FFTW_FORWARD,FFTW_MEASURE); | |
fftwf_execute(p); | |
} | |
end = system_clock::now(); | |
std::cout << "Optimized: " << duration_cast<milliseconds>(end-start).count() << std::endl; | |
} |
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