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Re: fft time in evm6678l

Liang Wen
Prodigy 45 points
Other Parts Discussed in Thread: TMS320C6670

from"TMS320C6670 Breakthrough performance for process-intensive applications"

 

C66x @1.2 GHz Single precision floating-point FFT, 2048 pt. radix 4 costs 14.60 us.

 

but the code in dsplib doesn't achieve this performance , maybe only half the speed...

i also don't know why...

  • TI__Expert 8055 points

    Can you provide more detail about the scenario?  What type of memory is the data located in?  How are you measuring performance?  With a simulator?  or some other way?  Are you running this on the EVM6670L?  Can you provide a cutdown project?

    Regards,

    Dan

     

  • in reply to DanRinkes
    Prodigy 45 points

    Hi, DanRinkes,

    I tried the code in "..\dsplib_c66x_3_0_0_8\packages\ti\dsplib\src\DSPF_sp_fftSPxSP\c66\DSPF_sp_fftSPxSP_66_LE_ELF" on EVM6678L

    here the result and the scenario:

    • [C66xx_0] DSPF_sp_fftSPxSP Iter#: 9 Result Successful N = 2048 radix = 2 natC: 97296 optC: 33197 cycles
    • [C66xx_0] DSPF_sp_fftSPxSP Iter#: 8 Result Successful N = 1024 radix = 4 natC: 40476 optC: 14762 cycles

     

    • both code and data (in, out, and twiddle factors) placed in L2 SRAM
    • ccxml: texas instruments xds100v1 usb emulator
    • I use clock() as well as on-chip Timer to measure performance, the results are almost the same
    and the project file: 7750.DSPF_sp_fftSPxSP.zip
    How can I replicate the results “C66x @1.2 GHz Single precision floating-point FFT, 2048 pt. radix 4 costs 14.60 us.” on EVM6678L?
    Thanks!
  • in reply to DanRinkes
    Prodigy 45 points

    it seems that use the code in dsplib within simulator will get the same result in the white paper...

    but the same code on evm board will get the cycle doubled...

    i don;t know why.... whether some special consideration or configuration is needed for the emulator board....

     

    thanks....