Hello All, I am trying to transmit on two UBX-160 daughterboards within a single X310 at 200 Msps using UHD 4.1.0.5-3.
I am experiencing periodic underflows, and I have already applied all of the tips in the "USRP Host Performance Tuning Tips and Tricks" application note, with the exception of using DPDK. I have a few questions about UHD streaming and what can be done to improve performance. 1. My current implementation uses a single tx_streamer for both channels, and uses multiple threads to populate the buffers sent to the X310. Would the performance be better if I used two separate streamers, one for each channel, in separate threads? 2. I have seen some claims that DPDK is not as useful with UHD 4, is this true? 3. With UHD 4, would it help to set the skip_duc and skip_ddc flags with full rate streaming? 4. Are underflows only created within the send() function? Or can the timing of calls to send() cause underflows, especially when the burst flags are used? For example, suppose I set the start of burst flag to true for a single buffer containing 1 second of data, and then I toggle the start of burst flag to false for subsequent buffers and continuously call send() on 1 second buffers for 10 minutes. On the last second I set end of burst flag to true. The idea is to create a 10 minute long "burst." If I call send late on one of the one second buffers in the middle of the "burst" will UHD report underflows? My thinking is the X310 should think it is in the middle of a burst, and will expect data, but send() has not been called, so there is no data for the radio to read from the host, creating underflows. Perhaps I am also misunderstanding the purpose of the burst flags, as they are not well documented. Thanks for the help! Armon
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