Hello community,
I am working on a gnuradio application that synchronously retrieves data
from a usrp_source, does some DSP on each of the streams and selects the
signal to send on a usrp_sink based on some metric computation. The sources
and sinks represent 3 USRP X310 devices, each with 2 UBX-160
daughterboards, and are synchronized using an Octoclock-G. Thus, creating a
6x1 MISO system. The USRP synchronization is done using the Python API, as
well as the flowgraph. The DSP blocks are coded in C++. The flowgraph would
be something like:
*self.connect((usrp_source, 0), my_dsp_0, (my_switch, 0))*
*self.connect((usrp_source, 1), my_dsp_1, (my_switch, 1))*
*self.connect((usrp_source, 2), my_dsp_2, (my_switch, 2))*
*self.connect((usrp_source, 3), my_dsp_3, (my_switch, 3))*
*self.connect(my_switch, another_dsp_0, (usrp_sink, 0))*
The application runs for a while until UHD outputs a message saying that
the poke32 has timed out on one of the USRP. After that, a misalignment
error on the receiver streams is shown and the green lights on the USRP go
off.
We are under the impression that the DSP blocks working independently may
be requesting samples from the source at different times, causing the
misalignment. Could this be the case? Is there an issue with my network
connection?
I have tried to get rid of the misalignment error by increasing the
threshold in the file
*{uhd_prefix}/host/lib/transport/super_recv_packet_handler.hpp, *through
the function *set_alignment_failure_threshold.* That got rid of the
misalignment error, but the failure coming from the poke function is still
there.
Interestingly, the exact same behavior arises when I just connect
file_sinks to the outputs from the usrp_source and a simple analog signal
to the usrp_sink. Below the flowgraph:
*self.connect((usrp_source, 0), file_sink_0)*
self.connect((usrp_source, 1), file_sink_1)
self.connect((usrp_source, 2), file_sink_2)
self.connect((usrp_source, 3), file_sink_3)
*self.connect(analog_sig_c, (usrp_sink, 0))*
I'd appreciate any help on this since I'm running out of ideas here.
Please, find below more details.
*The error:*
* [ERROR] [X300] 192.168.100.2 <http://192.168.100.2>: x300 fw
communication failure #1EnvironmentError: IOError: x300 fw poke32 - reply
timed out*
* [ERROR] [X300] 192.168.100.2 <http://192.168.100.2>: x300 fw
communication failure #1EnvironmentError: IOError: x300 fw poke32 - reply
timed out*
* [ERROR] [X300] 192.168.100.2 <http://192.168.100.2>: x300 fw
communication failure #3EnvironmentError: IOError: x300 fw poke32 - reply
timed out*
[ERROR] [UHD] An unexpected exception was caught in a task loop.The task
loop will now exit, things may not work.EnvironmentError: IOError:
192.168.100.2: x300 fw communication failure #3
* [ERROR] [STREAMER] The receive packet handler failed to time-align
packets.1002 received packets were processed by the handler.However, a
timestamp match could not be determined.*
*Here are some details of my network configuration:*
- UHD built from source, tag v3.14.1.1.
- Gnuradio built from source, tag 3.7.13.5.
- X310 USRP, each equipped with two UBX-160 daughterboards.
- The communication is over Ethernet using the 1Gb port on the X310.
- Each USRP is connected to a dedicated NIC.
- The MTU is set to 1500 for the all interfaces.
- The USRPs are synchronized using an Octoclock-G and the parameters tuned
in the Python script. The procedure is similar to the one followed in
benchmark_rate (uhd), for the usrp_source and usrp_sink.
- The NIC ring buffers are set to the maximum for both TX and RX, to 4096,
using ethtool.
- The OS ring buffers are set as suggested bu Ettus, using the following
commands:
*>> sudo sysctl -w net.core.rmem_max=33554432 >> sudo sysctl -w
net.core.wmem_max=33554432 >> sudo sysctl -w
net.core.rmem_default=33554432 >> sudo sysctl -w
net.core.wmem_default=33554432*
Best,
Carlos
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