Hello,

I am developing a custom c++ application (no GR) that takes data from the RX 
and  (for now) just pushes it to TX.  I am trying to achieve minimal latency 
(<<100 us).  The docs for X310 state that PCIe latency can be < 10 us.  I am 
not seeing that at all, the lowest I can get 350 us.

The setup is:

  *   Reset time to 0
  *   Set RX start time to 1.0000
  *   Set TX start time to 1 + DELTA
  *   Thread 1: read from RX streamer into a ring buffer
  *   Thread 2: read from ring buffer into TX streamer

NOTE: the threads are locked to cores and the process is given real-time 
priority.

Start lowering DELTA until we see 'L' packets.  I was able to get lower latency 
(180 us) using the 10 GbE interface, which should definitely not be the case!  
It has the network card latency + PCIe latency.

Using UHD 3.11

Can I set the PCIe transfer block size (like the frame size for UDP)?

Any other suggestions?

Thanks.

_______________________
Eugene Grayver, Ph.D.
Aerospace Corp., Sr. Eng. Spec.
Tel: 310.336.1274
________________________

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