[USRP-users] X300 underflows with tx_rate 100Msps

voonna santosh santu_voonna at yahoo.com
Thu Nov 21 12:34:45 EST 2019


Hi Michael,
    I am experiencing lots of underflows when I use benchmark_rate example app. Following is the configuration:
    
Host processor    : Intel® Xeon® Processor D-1500 System on Chip (SoC)
Host OS: Centos 7
UHD: release_003_010_001_000
SDR HW: X300 with UBX-160 (Calibration done as documented)
Eth link: SFP
 - Maximum socket buffer sizes (wmem_max, rmem_max)
 - MTU 9000
 - Tx/Rx descriptors (sudo ethtool -G <interface> tx 4096 rx 4096)
 - thread priority set to 1
CPU usage: Only two CPUs are being used, but rest of the cores are free and the host is headless(No CPU consuming apps).

  If I test rx_rate with 200Msps, it works well. But when I use tx_rate with 100Msps, I could see lots of underflows (Us).

./benchmark_rate --args="addr=192.168.40.2" --tx_rate=100e6  --channels="0" --duration 200
linux; GNU C++ version 4.8.5 20150623 (Red Hat 4.8.5-39); Boost_105800; UHD_003.010.001.HEAD-0-g929e3b32


Creating the usrp device with: addr=192.168.40.2...
-- X300 initialization sequence...
-- Determining maximum frame size... 8000 bytes.
-- Setup basic communication...
-- Loading values from EEPROM...
-- Setup RF frontend clocking...
-- Radio 1x clock:200
-- Detecting internal GPSDO.... Found an internal GPSDO: LC_XO, Firmware Rev 0.929b
-- [DMA FIFO] Running BIST for FIFO 0... pass (Throughput: 1179.5MB/s)
-- [DMA FIFO] Running BIST for FIFO 1... pass (Throughput: 1184.4MB/s)
-- [RFNoC Radio] Performing register loopback test... pass
-- [RFNoC Radio] Performing register loopback test... pass
-- [RFNoC Radio] Performing register loopback test... pass
-- [RFNoC Radio] Performing register loopback test... pass
-- Performing timer loopback test... pass
-- Performing timer loopback test... pass
Using Device: Single USRP:
  Device: X-Series Device
  Mboard 0: X300
  RX Channel: 0
    RX DSP: 0
    RX Dboard: A
    RX Subdev: UBX RX
  RX Channel: 1
    RX DSP: 0
    RX Dboard: B
    RX Subdev: Unknown (0xffff) - 0
  TX Channel: 0
    TX DSP: 0
    TX Dboard: A
    TX Subdev: UBX TX
  TX Channel: 1
    TX DSP: 0
    TX Dboard: B
    TX Subdev: Unknown (0xffff) - 0

Setting device timestamp to 0...
Testing transmit rate 100.000000 Msps on 1 channels
UUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUUU ....... Lots of underflows

Thanks in advance.
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