Kissfft on parallella

[Krisania]

Hello,
I'm currently just starting out working on the parallella board, haven't worked another project on it before so not a lot of experience here, please be patient with me
What I'm trying to do is run an fft algorithm on the board. I've been using the kissfft libraries, working exclusively on the arm part of the board and it seems to be working fine. However, as a next step I want to use the epiphany cores to execute the fft. My point here though, and what's different from other threads I've seen, is, I don't want to parallellize the fft itself, I just want to run seperate ffts in seperate data, in parallell.
Is there a working version of what I described doable? When I try to run the kissfft on the cores the program seems to hang (possibly due to memory allocation problems that kissfft uses internally?)

[jar]

Each core has 32 KB of SRAM shared between instructions, data, and stack. Your code will pay a hefty penalty for exceeding that. How large are your FFTs?

[Krisania]

[jar]

1000 FFTs... Are you operating on data from DRAM?

If you can publish the code, it would help.

[Krisania]

[jar]

I quickly scanned your code, but didn't try running it. It looks like you've hard coded addresses for your data, which probably overlap your instructions. Your cores may be trying to execute "data", not instructions. It looks like the code may also call printf, which might cause problems. Also, your code seems to be calling malloc.

[Krisania]

[sebraa]

Hi,

I don't think that using malloc() on the Epiphany cores is a good idea. Dynamic memory might be allocated in shared memory, which has different access semantics, which will cause your code to fail. There are provisions for using alloca() instead, but I don't know if this replaces all malloc()-calls. Try it.

Check your program size. If you put your data at 0x2000, then your whole kernel must be smaller than 8 KB. Try using a higher address, but make sure that your data does not overlap either your program (easy to check) or the stack (harder to check, if using alloca).

Also, quite some time ago, I released a program called e-top on this forum. Search for it, it might help you see what's going on within the cores.

Best Regards,
sebraa