Question

我正在尝试使用FFTW的Wisdom功能来更快地创建FFTW计划。智慧似乎正确地保存并正确加载，但它并没有加快后续运行的创建速度。此外，如果我尝试使用WISDOM_ONLY标志创建计划，它会返回一个NULL计划，让我知道即使加载智慧的调用工作正常，也无法用它来制定计划。

如果我多次运行以下代码，第一次无法加载智慧文件（因为它不存在），并且在后续运行中它会报告它已正确加载。在每次运行时，首先或之后，创建FFTW计划需要相同的时间。

#include <Windows.h>
#include <omp.h>

#include "fftw3.h"

#define THREADS 4

int main ()
{
   LARGE_INTEGER li, li2;
   __int64 init, run;
   double freq;

   int Xfft = 384;
   int Yfft = 384;
   int iterations = 1000;
   fftwf_plan pFft[THREADS];

   QueryPerformanceFrequency ( &li );
   freq = (double)li.QuadPart / 1000000.0;

   // Malloc buffer
   fftwf_complex* arr[THREADS];

   for ( int i = 0; i < THREADS; i++)
   {
      arr[i] = (fftwf_complex*) fftwf_malloc ( sizeof(fftwf_complex) * Xfft * Yfft );
   }

   // Setup FFT plan
   QueryPerformanceCounter ( &li );

   if (fftw_import_wisdom_from_filename("fftw.wis") == 1 )
   {
      printf("SUCCESS!\n");
   }
   else
   {
      printf("FAILURE!\n");
   }

   for ( int i = 0; i < THREADS; i++ )
   {
      pFft[i] = fftwf_plan_dft_2d ( Xfft, Yfft, arr[i], arr[i], FFTW_FORWARD, FFTW_PATIENT );
   }

   fftw_export_wisdom_to_filename("fftw.wis");

   QueryPerformanceCounter ( &li2 );
   init = li2.QuadPart - li.QuadPart;

   // Init array to random numbers
   for ( int i = 0; i < THREADS; i++ )
      for ( int j = 0; j < Xfft * Yfft; j++ )
      {
         arr[i][j][0] = (float)rand();
         arr[i][j][1] = (float)rand();
      }

   omp_set_num_threads(THREADS);

   // Perform FFTs
   QueryPerformanceCounter ( &li );

   #pragma omp parallel
   {
      int ID = omp_get_thread_num();

      #pragma omp for
      for ( int i = 0; i < iterations; i++ )
      {
         fftwf_execute ( pFft[ID] );
      }
   }

   QueryPerformanceCounter ( &li2 );
   run = li2.QuadPart - li.QuadPart;

   // Free Buffer / destroy plan
   for ( int i = 0; i < THREADS; i++ )
   {
      fftwf_destroy_plan ( pFft[i] );
      fftwf_free ( arr[i] );
   }

   printf ( "Plan creation time: %6.4f microseconds\n", (double)init / freq );
   printf ( "FFT execution time: %6.4f microseconds\n", (double)run  / freq / (double)iterations );

   system( "pause" );

   return EXIT_SUCCESS;
}

FFTW智慧不起作用

0 个答案: