[USRP-users] USRP X310 Maximum frame size: 7972 bytes.

akin soysal akinsoysal at gmail.com
Wed Feb 20 07:50:52 EST 2019


Hello,

In order to decrease the latency, I was playing around with the MTU size
setting it to 4000, 7000, 9000 and now a permanent error happens in my
server connected to USRP. I tried it with two different USRP X310s and the
problem happens in both. Where does the 7972 bytes come from? Thanks.
Regards, Akın

/uhd/uhd/host/build$ uhd_usrp_probe
[INFO] [UHD] linux; GNU C++ version 5.4.0 20160609; Boost_105800;
UHD_3.13.1.HEAD-0-gbbce3e45
[INFO] [X300] X300 initialization sequence...
[INFO] [X300] Maximum frame size: 7972 bytes.
[INFO] [X300] Radio 1x clock: 200 MHz
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[INFO] [0/DmaFIFO_0] Initializing block control (NOC ID: 0xF1F0D00000000000)
[INFO] [0/DmaFIFO_0] BIST passed (Throughput: 1306 MB/s)
[INFO] [0/DmaFIFO_0] BIST passed (Throughput: 1311 MB/s)
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[INFO] [0/Radio_0] Initializing block control (NOC ID: 0x12AD100000000001)
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[INFO] [0/Radio_1] Initializing block control (NOC ID: 0x12AD100000000001)
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[INFO] [0/DDC_0] Initializing block control (NOC ID: 0xDDC0000000000000)
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[INFO] [0/DDC_1] Initializing block control (NOC ID: 0xDDC0000000000000)
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[INFO] [0/DUC_0] Initializing block control (NOC ID: 0xD0C0000000000000)
[WARNING] [X300] For this connection, UHD recommends a send frame size of
at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[WARNING] [X300] For this connection, UHD recommends a receive frame size
of at least 8000 for best
performance, but your system's MTU will only allow 7972.This will
negatively impact your maximum achievable sample rate.
[INFO] [0/DUC_1] Initializing block control (NOC ID: 0xD0C0000000000000)
  _____________________________________________________
 /
|       Device: X-Series Device
|     _____________________________________________________
|    /
|   |       Mboard: X310
|   |   revision: 11
|   |   revision_compat: 7
|   |   product: 30818
|   |   mac-addr0: 00:80:2f:22:c1:70
|   |   mac-addr1: 00:80:2f:22:c1:71
|   |   gateway: 10.10.1.1
|   |   ip-addr0: 10.10.1.2
|   |   subnet0: 255.255.255.0
|   |   ip-addr1: 10.10.1.3
|   |   subnet1: 255.255.255.0
|   |   ip-addr2: 10.10.1.4
|   |   subnet2: 255.255.255.0
|   |   ip-addr3: 10.10.1.5
|   |   subnet3: 255.255.255.0
|   |   serial: 316FCFF
|   |   FW Version: 6.0
|   |   FPGA Version: 35.1
|   |   FPGA git hash: d0360f7
|   |   RFNoC capable: Yes
|   |
|   |   Time sources:  internal, external, gpsdo
|   |   Clock sources: internal, external, gpsdo
|   |   Sensors: ref_locked
|   |     _____________________________________________________
|   |    /
|   |   |       RX Dboard: A
|   |   |   ID: CBX-120 (0x0085)
|   |   |   Serial: 316BB64
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       RX Frontend: 0
|   |   |   |   Name: CBX-120 RX
|   |   |   |   Antennas: TX/RX, RX2, CAL
|   |   |   |   Sensors: lo_locked
|   |   |   |   Freq range: 1200.000 to 6000.000 MHz
|   |   |   |   Gain range PGA0: 0.0 to 31.5 step 0.5 dB
|   |   |   |   Bandwidth range: 120000000.0 to 120000000.0 step 0.0 Hz
|   |   |   |   Connection Type: IQ
|   |   |   |   Uses LO offset: No
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       RX Codec: A
|   |   |   |   Name: ads62p48
|   |   |   |   Gain range digital: 0.0 to 6.0 step 0.5 dB
|   |     _____________________________________________________
|   |    /
|   |   |       RX Dboard: B
|   |   |   ID: CBX-120 (0x0085)
|   |   |   Serial: 3177160
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       RX Frontend: 0
|   |   |   |   Name: CBX-120 RX
|   |   |   |   Antennas: TX/RX, RX2, CAL
|   |   |   |   Sensors: lo_locked
|   |   |   |   Freq range: 1200.000 to 6000.000 MHz
|   |   |   |   Gain range PGA0: 0.0 to 31.5 step 0.5 dB
|   |   |   |   Bandwidth range: 120000000.0 to 120000000.0 step 0.0 Hz
|   |   |   |   Connection Type: IQ
|   |   |   |   Uses LO offset: No
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       RX Codec: B
|   |   |   |   Name: ads62p48
|   |   |   |   Gain range digital: 0.0 to 6.0 step 0.5 dB
|   |     _____________________________________________________
|   |    /
|   |   |       TX Dboard: A
|   |   |   ID: CBX-120 (0x0084)
|   |   |   Serial: 316BB64
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       TX Frontend: 0
|   |   |   |   Name: CBX-120 TX
|   |   |   |   Antennas: TX/RX, CAL
|   |   |   |   Sensors: lo_locked
|   |   |   |   Freq range: 1200.000 to 6000.000 MHz
|   |   |   |   Gain range PGA0: 0.0 to 31.5 step 0.5 dB
|   |   |   |   Bandwidth range: 120000000.0 to 120000000.0 step 0.0 Hz
|   |   |   |   Connection Type: QI
|   |   |   |   Uses LO offset: No
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       TX Codec: A
|   |   |   |   Name: ad9146
|   |   |   |   Gain Elements: None
|   |     _____________________________________________________
|   |    /
|   |   |       TX Dboard: B
|   |   |   ID: CBX-120 (0x0084)
|   |   |   Serial: 3177160
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       TX Frontend: 0
|   |   |   |   Name: CBX-120 TX
|   |   |   |   Antennas: TX/RX, CAL
|   |   |   |   Sensors: lo_locked
|   |   |   |   Freq range: 1200.000 to 6000.000 MHz
|   |   |   |   Gain range PGA0: 0.0 to 31.5 step 0.5 dB
|   |   |   |   Bandwidth range: 120000000.0 to 120000000.0 step 0.0 Hz
|   |   |   |   Connection Type: QI
|   |   |   |   Uses LO offset: No
|   |   |     _____________________________________________________
|   |   |    /
|   |   |   |       TX Codec: B
|   |   |   |   Name: ad9146
|   |   |   |   Gain Elements: None
|   |     _____________________________________________________
|   |    /
|   |   |       RFNoC blocks on this device:
|   |   |
|   |   |   * DmaFIFO_0
|   |   |   * Radio_0
|   |   |   * Radio_1
|   |   |   * DDC_0
|   |   |   * DDC_1
|   |   |   * DUC_0
|   |   |   * DUC_1
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