topic Re: IPP FFT and OpenMP in Intel® Integrated Performance Primitives

IPP FFT and OpenMP

amcelroy — Thu, 17 Apr 2008 16:49:24 GMT

Hello everyone,

I would like to combine OpenMP and the FFT code and had a quick question. I havea for loop that is executing an FFT routine multiple times, but when it gets to the actual FFT routine, I have only allocated 1 memory space (see code) which all threads need to share, which is non-ideal.

IppsFFTSpec_R_32f* spec;

ippsFFTInitAlloc_R_32f(&spec, x, IPP_FFT_DIV_FWD_BY_N, ippAlgHintFast);

omp_set_num_threads(2);

#pragma

omp parallel for

for(int counter = 0; counter < 10000; counter++)

{

//I would like to allocate and copy the spec table so that the loops are independant

ippsFFTFwd_RToPerm_32f((float*)ptrFFTVector, (float*)ptrFFTVector, spec, 0);

}

The question is, how can I allocate and copy the spec space into another, loop independant local variable. In the IPP, there is a command to initialize an FFT table, a command to allocate memoryand initialize a table, but no command to allocate and copy a table. How can I do this?

Thanks in advance,

Austin

Re: IPP FFT and OpenMP

Vladimir_Dudnik — Thu, 24 Apr 2008 19:33:56 GMT

Hi Austin,

our experts said that you not necessary need to copy FFT spec for each thread. By IPP conventions, Spec is read-only data. So all threads can share the same Spec

Regards,
Vladimir

Re: IPP FFT and OpenMP

you7878 — Sun, 27 Apr 2008 06:38:45 GMT

Hello Experts
How about speed? Will it slow down calculations? Maybe it is more comfortable to have separate copy of FFT table for each thread? Even if I am using architecture with shared memory - Quad Core.
Thanks