Can you replace the DMA FIFO with a normal FIFO? The DMA FIFO is mostly used for continuous streaming-- it provides a data buffer using off-chip DRAM that smooths out any burstiness in the ethernet interface so there's no overflows/underruns-- but it should not be needed for your application.
You might try the following rfnoc graph: Host -> FFT -> FIFO -> Host With that graph you'll be able to directly observe the latency presented to the FFT block by the ethernet transport only. Using a 1G interface for a packet of 8192 bytes gives a theoretical best one way latency of 65 us... It is a long way from 200 us-- but already higher than the FFT compute time. Finally, I will add... in my opinion using rfnoc explicitly as a network-attached coprocessor is probably not an ideal use case. I will often set up loopback tests like you are doing here, but mostly this is to validate custom compute blocks and I don't care about latency. Afterwards I will embed the blocks into stream processing that's attached directly to a radio. Best regards, EJ On Wed, Dec 30, 2020, 4:15 AM Jorge Arroyo Giganto via USRP-users < usrp-users@lists.ettus.com> wrote: > Hi Nick, > > I am running the X310 interface at 1Gbit using the SFP Adapter that came > with the X310. > > At first I fowollowed the advice from Ettus USRP Manual > <https://files.ettus.com/manual/page_usrp_x3x0_config.html#x3x0cfg_hostpc_netcfg_mtu> > of setting the MTU to 1500 and <send/recv>_frame_size=1472 when running at > 1Gbit, however I actually got better results in terms of latency setting > the MTU to 9000 and <send/recv>_frame_size=8000. I also tried using other > intermediate and smaller values but the results didn't get any better. > > Best regards, > > Jorge > _______________________________________________ > USRP-users mailing list > USRP-users@lists.ettus.com > http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com >
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