[USRP-users] rec_samples_to_file overflow

Marcus D. Leech mleech at ripnet.com
Thu Mar 24 11:53:13 EDT 2016

On 03/24/2016 11:39 AM, Xingjian Chen via USRP-users wrote:
> Hello guys.
> I set B200mini receiving samples using UHD example called "rx_samples_to_file.cpp" at rate of 56MB/s with float32 I/Q data. It always get overflow message as below:
> "Got an overflow indication. Please consider the following:
>    Your write medium must sustain a rate of 448.000000MB/s.
>    Dropped samples will not be written to the file.
>    Please modify this example for your purposes.
>    This message will not appear again."
> However, my memory speed is over 3 GB/s according to the test using the method here:
> http://serverfault.com/questions/372020/what-are-the-best-possible-ways-to-benchmark-ram-no-ecc-under-linux-arm
> I find the problem is from this sentence in the rx_samples_to_file.cpp:
> size_t num_rx_samps = rx_stream->recv(&buff.front(), buff.size(), md, 3.0, enable_size_map);
> I guess the rx_stream command does not utilizing all my memory capability. Any ideas?
> Thank you!
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Are you writing to a file on a ramdisk, or just a regular disk?

Unless you have a RAID array, it would be very difficult to sustain 
448MB/sec write rates to a single disk.

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