[Discuss-gnuradio] uhd_two_tone_loopback.grc example

For this "uhd_two_tone_loopback.grc" example, it runs great at 500k samling_rate. However, when I increase the sampling rate to 50M, I start to get printouts on the screen: "UUU...", and it is very hard to stop the running example. Besides, when it runs at 500K sampling_rate, no printouts on the screen. Therefore, it is very easy to stop the application at 500K. I got similar results for other applications written by myself.

What could be the reason that causes the printouts at higher sampling_rate? Is there a solution for this problem? As I understand, 50M sampling_rate should be acceptable for my device.

Thanks in advance.