> Date: Mon, 15 Jan 2018 16:26:59 -0800
> From: Martin Braun <[email protected]>
> To: [email protected]

> Dmitry,
> 
> 2x200e6 is extremely hard to maintain from software, and we haven't
> been
> able to sustain such rates ourselves. We are looking into it, but
> don't
> expect any radical improvements any time soon.

This almost certainly a Linux network stack and NIC driver TX queuing
problem.

See my rambling here for things to do (for at least a single 10 GBE
interface):

https://github.com/EttusResearch/uhd/issues/102#issue-236687315

The actual settings to use depend very much on your system.

-Andy

> However, that explains Us, not Ss. Can you run ifconfig to see if the
> NIC is dropping packets?
> 
> Thanks,
> Martin
> 
> On 01/12/2018 09:10 AM, ??????? ???????????? via USRP-users wrote:
> > Hi,
> > 
> > I am unable to transmit two channels simultaneously without flow
> > errors.
> > I have X310 with dual 10 Gige interface installed, the image was
> > uploaded from usrp_x310_fpga_XG.bit file. Every time I run
> > benchmark
> > utility to transmit two channels at the full rate I get a lot of
> > 'S' and
> > then 'U'. There are no problems with receiving two channels or
> > transmitting just one channel.
> > 
> > 
> > $ sudo /usr/local/lib/uhd/examples/benchmark_rate --args
> > "addr=192.168.30.2,second_addr=192.168.40.2"?? --tx_rate 200e6
> > --tx_channels 0,1
> > 
> > [INFO] [UHDlinux; GNU C++ version 4.8.4; Boost_105400;
> > UHD_4.0.0.rfnoc-devel-376-g5a982809]
> > Creating the usrp device with:
> > addr=192.168.30.2,second_addr=192.168.40.2...
> > [INFO] [X300] X300 initialization sequence...
> > [INFO] [X300] Determining maximum frame size...
> > [INFO] [X300] Maximum frame size: 8000 bytes.
> > [INFO] [X300] Determining maximum frame size...
> > [INFO] [X300] Maximum frame size: 8000 bytes.
> > [INFO] [X300] Setup basic communication...
> > [INFO] [X300] Loading values from EEPROM...
> > [INFO] [X300] Setup RF frontend clocking...
> > [INFO] [X300] Radio 1x clock:200
> > [INFO] [RFNOC] [DMA FIFO] Running BIST for FIFO 0...
> > [INFO] [RFNOC] pass (Throughput: 1304.3MB/s)
> > [INFO] [RFNOC] [DMA FIFO] Running BIST for FIFO 1...
> > [INFO] [RFNOC] pass (Throughput: 1304.5MB/s)
> > [INFO] [RFNOC RADIO] Register loopback test passed
> > [INFO] [RFNOC RADIO] Register loopback test passed
> > [INFO] [RFNOC RADIO] Register loopback test passed
> > [INFO] [RFNOC RADIO] Register loopback test passed
> > [INFO] [CORES] Performing timer loopback test...
> > [INFO] [CORES] Timer loopback test passed
> > [INFO] [CORES] Performing timer loopback test...
> > [INFO] [CORES] Timer loopback test passed
> > Using Device: Single USRP:
> > ? Device: X-Series Device
> > ? Mboard 0: X310
> > ? RX Channel: 0
> > ??? RX DSP: 0
> > ??? RX Dboard: A
> > ??? RX Subdev: SBX-120 RX
> > ? RX Channel: 1
> > ??? RX DSP: 0
> > ??? RX Dboard: B
> > ??? RX Subdev: SBX-120 RX
> > ? TX Channel: 0
> > ??? TX DSP: 0
> > ??? TX Dboard: A
> > ??? TX Subdev: SBX-120 TX
> > ? TX Channel: 1
> > ??? TX DSP: 0
> > ??? TX Dboard: B
> > ??? TX Subdev: SBX-120 TX
> > 
> > Setting device timestamp to 0...
> > [INFO] [MULTI_USRP]???? 1) catch time transition at pps edge
> > [INFO] [MULTI_USRP]???? 2) set times next pps (synchronously)
> > Testing transmit rate 200.000000 Msps on 2 channels
> > SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS.....
> > 
> > If I reduce sample rate to 100 Msps there are only 'U' errors left.
> > With
> > lower rate (10 Msps) errors disappear. Does X310 allow to transmit
> > two
> > 200 Msps channels simultaneously?
> > 
> > 
> > thanks,
> > Dmitry
> > 

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