On 2021-11-30 19:14, Jonathan Pratt wrote:
Have looked into the benchmark rate utility (uhd/host/build/examples/)
which shows dropouts at any sample rate above 2MSPS. Have also run the
same thing from a PC laptop running ubuntu 20.04 in a virtual machine
with the same gnuradio (3.8), same uhd (4.0.0) and same gr-ettus
(RFNoC 4). It also flags dropouts consistently at any sample rate
above 2MSPS. The fpga image for the X310 was downloaded and installed
according to the instructions in the hardware manual
(https://files.ettus.com/manual/page_usrp_x3x0.html). It appears to us
that the issue lies with something to do with the X310 or software
that is communicating with it, or the fpga image.
Is there any setup item we can change to get net traffic without
dropouts? Will there be a problem if we don’t drain data from the
other receives at the same time since there are four of them?
Thanks
Jonathan Pratt
LOTS of people on this list *routinely* stream data out of their X310s
even over 1Gbit links at MUCH MUCH higher sample rates. What kind of
1Gbit or 10Gbit interface do you
have? Are you using the SFP+ ports or the RJ-45 port?
What kind of computer is this on? We generally DO NOT recommend virtual
machine implementations because the performance tends to suffer,
PARTICULARLY
the Network and USB performance.
*From:*Marcus D. Leech <[email protected]>
*Sent:* Tuesday, 30 November 2021 10:35 AM
*To:* [email protected]
*Subject:* [USRP-users] Re: USRP streaming data performance
*WARNING:***This message has originated from an untrusted source. Be
mindful of attachments and embedded links.
On 2021-11-29 18:22, Jonathan Pratt wrote:
We are looking to develop a standalone sdr platform connecting an
nVidia Jetson AGX Xavier to a USRP X310. The X310 has two dual
receiver boards installed but we are only trying to stream data
from one core at this time.
The Xavier is an octacore ARM platform with all cores enabled and
running close to 1.5GHz.
The connection between the two devices is via ethernet running at
1Gbit. The xavier has a x16 PCIe interface connector and we are
using a NIC with 1Gbps SFP module – we intend to run the link at
10Gbit in the future. The onboard 1Gbps ethernet is connected to
our LAN
The Xavier is running ubuntu 18.04 for arm. This is the
development platform that nVidia provides. uhd 4.0.0, gnuradio 3.8
and RfNoC 4 have been installed on the Xavier.
The Xavier is given a simple flow to run under gnuradio-companion
which consists of a USRP Source connected directly to the QT GUI
Frequency sink (or Null Sink)
The network buffers and mtu on the xavier are increased to at
least those recommended.
The result we get is a whole lot of ‘D’s output if we increase the
sample rate beyond 2MSPS. The same result is found if we run the
flow from the command line (without the gui).
For comparison we have done a similar setup with a USRP E312 –
connected to a xavier, a ubuntu 20 virtual machine and directly to
a computer running ubuntu 20.04. In each case when we increase the
sample rate beyond 2MSPS we get ‘O’s output.
Can anyone please indicate what setup is required to achieve the
25MSPS that should be possible across this link?
Thanks in advance
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You might want to run "benchmark_rate" from the UHD examples code to
eliminate GR entirely at first--just to get a feel for what your
machine is capable of.
I'll note that the "network mode" in E312 (where it streams to a
regular PC) has *considerable* performance constraints, and achieving
even 2Msps is a bit of a
miracle.
The X310, on the other hand, is Niagara Falls. Any
streaming-performance issues are your host. The FPGA on the X310 can
stream to the xGIGe interfaces as fast as
physics allows, pretty much.
For a "order of magnitude" benchmark, I can achieve 10Msps from a B2xx
into an Odroid XU4Q with 8-bit samples (there's a USB bandwidth issue
there). I can even
"do stuff" at 10Msps, including several different radio astronomy
signal processing chains. I would expect your Xavier to be similar.
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