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Diffstat (limited to 'host/docs/general.dox')
| -rw-r--r-- | host/docs/general.dox | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/host/docs/general.dox b/host/docs/general.dox index 2dab0a9ea..4e1d0cfb9 100644 --- a/host/docs/general.dox +++ b/host/docs/general.dox @@ -189,6 +189,18 @@ Underflow occurs when the host does not produce data fast enough. When UHD software detects the underflow, it prints a "U" to stdout, and pushes a message packet into the async message stream. +Some underruns may be mitigated by buffering data in DRAM using the Replay +block. The Replay block is only available in devices that support RFNoC. Some +RFNoC devices include the Replay block in the default FPGA image. Use the +'uhd_usrp_probe' utility and look for the "RFNoC blocks on this device:" +section of the output to check if the Replay block is present. If using +the multi_usrp API, simply add the stream argument "streamer=replay_buffered" +to enable the buffering. This buffering adds latency and will likely not work +at the highest streaming rates. A limited number of buffers can be stored +in the Replay block, so larger buffers supplied to the tx_streamer::send() +call will produce the best results. Buffers that are too small will result +in gaps in the transmitted signal. + <b>Note:</b> "O" and "U" message are generally harmless, and just mean the host machine can't keep up with the requested rates. |