They are connected to each other over wired ethernet via Tobi boards.
They each have a capture device plugged in by USB.
I connect wirelessly to Gumstix A or B, one at a time.
I stream video from either Gumstix A or B, one at a time.
If I connect wirelessly to Gumstix A, and stream video from Gumstix B, the video data comes over the wired ethernet and is routed through Gumstix A over wifi back to the laptop. Occasionally, I will see dropped RX packets on eth0 on Gumstix A. When the packets drop, the video flickers.
If I connect wirelessly to Gumstix A and stream video from Gumstix A, the video never flickers. In this case the wired ethernet is not involved at all.
Likewise, if I stream A's video while connected wirelessly to B, I get flicker, but if I stream B's video while connected to B, I get no flicker.
I tried to increase the ring buffer size on the smsc9221 to no avail:
root@sbcA:~# ./ethtool -G eth0
Cannot get device ring settings: Operation not supported
Can anyone suggest other options for mitigating this problem with dropped RX packets on eth0?
Solved this by turning off the cpufreq "ondemand" governor.
My cpu load is low, so usually the governor has the clock at 125MHz. But occasionally the ethernet RX buffer isn't emptied fast enough, and packets are dropped. I noticed that if I artificially increased the cpu load, my streaming issues would disappear, I guess because the clockrate was higher.