我正在尝试并行执行多个傅里叶变换(FFT)。我正在使用FFTW和OpenMP。每个FFT都不同,因此我不依赖于FFTW的内置多线程(我知道它使用OpenMP)。
int m;
// assume:
// int numberOfColumns = 100;
// int numberOfRows = 100;
#pragma omp parallel for default(none) private(m) shared(numberOfColumns, numberOfRows)// num_threads(4)
for(m = 0; m < 36; m++){
// create pointers
double *inputTest;
fftw_complex *outputTest;
fftw_plan testPlan;
// preallocate vectors for FFTW
outputTest = (fftw_complex*)fftw_malloc(sizeof(fftw_complex)*numberOfRows*numberOfColumns);
inputTest = (double *)fftw_malloc(sizeof(double)*numberOfRows*numberOfColumns);
// confirm that preallocation worked
if (inputTest == NULL || outputTest == NULL){
logger_.log_error("\t\t FFTW memory not allocated on m = %i", m);
}
// EDIT: insert data into inputTest
inputTest = someDataSpecificToThisIteration(m); // same size for all m
// create FFTW plan
#pragma omp critical (make_plan)
{
testPlan = fftw_plan_dft_r2c_2d(numberOfRows, numberOfColumns, inputTest, outputTest, FFTW_ESTIMATE);
}
// confirm that plan was created correctly
if (testPlan == NULL){
logger_.log_error("\t\t failed to create plan on m = %i", m);
}
// execute plan
fftw_execute(testPlan);
// clean up
fftw_free(inputTest);
fftw_free(outputTest);
fftw_destroy_plan(testPlan);
}// end parallelized for loop
所有的都很好,但是如果我从计划创建周围移除关键结构(fftw_plan_dft_r2c_2d),我的代码将失败。有人能解释一下为什么吗?fftw_plan_dft_r2c_2d不是一个“孤儿”,对吧?是因为两个线程可能同时尝试命中numberOfRows或numberOfColumns内存位置吗?