Lab: AXI4-Burst problem on latency

[JiaMingLin]

Hi, I copied your Lab of AXI4-Burst and followed your instructions to port to PYNQ-Z2. However, I am not sure how to measure the latency(I want to report the latency of different burst lengths).

I have tried one, and following is my method,

• put following lines into a Python function, e.g.

    def exec(length):
        sqrt_ip.write(0x20, length)
        sqrt_ip.write(0x10, inpt.physical_address)
        sqrt_ip.write(0x18, outpt.physical_address)
        sqrt_ip.write(0x00, 1)
  

• Then using %timeit exec(length) to report execution time.
• I modified the length from 100 to 32768 (I have modified the HLS code from SIZE=100 to SIZE=32768)

However, the results of %timeit exec(length) are almost the same from 120~130 mu-sec for the hardware configs SIZE=100 or SIZE=32768.

Then my question is how to evaluate the latency from PYNQ correctly?

Thanks