WARNING UDP The recv buffer could not be resized sufficiently. Target sock buff size: 250000000 bytes. Actual sock buff size: 212992 bytes. See the transport application notes on buffer resizing. Please run: sudo sysctl -w net.core.rmem_max=250000000 WARNING UDP The send buffer could not be resized sufficiently. Target sock buff size: 250000000 bytes. Actual sock buff size: 212992 bytes. See the transport application notes on buffer resizing. Please run: sudo sysctl -w net.core.wmem_max=250000000 WARNING UDP The current recv_buff_size of 212992 is less than the minimum recommended size of 307200 and may result in dropped packets on some NICs WARNING UDP The current send_buff_size of 212992 is less than the minimum recommended size of 307200 and may result in dropped packets on some NICs
🔧 临时解决方法（当前会话有效）
在 Spark 机器上（root 权限）执行：
sudo sysctl -w net.core.rmem_max=250000000
sudo sysctl -w net.core.wmem_max=250000000
可以先看看现在的值：
sysctl net.core.rmem_max
sysctl net.core.wmem_max
改完后再跑 USRP 程序，一般这些 WARNING 就会消失。
注意：这是"内核最大值"，UHD 仍然会按自己设定去申请 buffer，申请值不能超过这个上限。
🔁 持久化配置（重启后也生效）
编辑 /etc/sysctl.d/uhd.conf（文件名随便，只要在这个目录里即可）：
sudo nano /etc/sysctl.d/uhd.conf
写入：
net.core.rmem_max = 250000000
net.core.wmem_max = 250000000
保存后执行：
sudo sysctl --system
这样以后开机就自动是这个配置。