[USRP-users] Fifo ctrl timed out looking for acks

Paul Pruitt paul at pseudonoise.net
Thu Feb 14 14:49:40 EST 2013

I'm getting this exception, thrown from
usrp2_fifo_ctrl_impl::wait_for_acks, sometimes after several hours of

The device is an N210 with UHD version 003:005.000-26-gb65a3924 on a laptop
under CentOS 6.3 64-bit. I'm collecting 100 ms duration streams from both
channels at 10 MSPS (each) every 250 ms.

As an experiment, I increased ACK_TIMEOUT from 0.5 s to 5.5 s. The
exception still occurred. No ethernet errors or dropped packets are
reported by ifconfig. I am running as root and verified the threads are
running at realtime priority with htop. The frame sizes, recv_frame_size
and send_frame_size, are set to 4095 bytes. Kernel rx/tx socket buffers are

Any idea what might be causing this?
Is it safe to catch the exception and keep going? If I restart my program
after the exception, the USRP works fine.

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