Beaglebone Black + FreeBSD + USB WiFi = WAP?

[Chris Gordon]

Russ,

> Have you monitored your system on a serial console or direct console
> (i.e. via hdmi/keyboard)? Is the system still responding to other
> commands after you run the speed test? My thought is that the really
> really low bandwidth belies a kernel panic on the main terminal that
> you are not seeing.

I have a serial console connected the entire time along with ssh sessions (via wired NIC) into the BBB.  There is no panic other other messages on the console.  The devices remains responsive to user input/actions via ssh. In a previous reply to my initial inquiry, Ilya Bakulin asked about output from "top -Sa” thinking the CPU was overwhelmed.  The system stays at >90% idle through the entire test (upload and download).  I see 2-4% WCPU for interrupts and 1-2% for USB.

> If you would like to do some further testing, you could perhaps help
> me answer these things:

It won’t be until next week when I can look at any of these.  I’m one of the organizers at vBSDcon and will be at the Dev Summit and conference through the weekend.  If anyone is interested, I’m happy to bring my BBB there for debugging/testing on site.

> - Can you find a command line way of measuring throughput and latency
> separately that can be run on a host and on the bbb? I'm sure there
> are lots of ways to do so. I will leave it up to you to decide and
> will adopt the same tests so we can compare results.

I just have to find another device -- I have everything wired here other than i-devices.  I used nuttcp for testing the wired connection, so I would plan to use that for the Wifi.

> - Can you run the bbb as a standard device (not an access point) and
> test the performance of the wlan0 interface using the method of
> measurement pointed above? I will do the same at some point with my
> wi-fi dongle.

Yes, that should be easy to do, but will be next week before I have a chance.

> Some tests I would like to do:
> - Get DTrace involved as a debugging tool. I have rudimentary DTrace
> skills but will need to consult my books on how to measure throughput
> and latency. There are some examples early in the DTrace book of
> logging system calls made by a process and I will review that again
> when time permits.
> - Run the system through the kernel debugger. I think this is going to
> be difficult though as pausing the kernel in the middle of TCP traffic
> might invalidate any results I get. I know how difficult it can be to
> debug threaded applications, I can't see a kernel being any easier. ;)

I was thinking along the same lines and hampered only by lack of time and specific knowledge of what to start poking (of course, this is a great wqy to learn!).

Thanks for your help.  I’ll get some info as soon as I can.  Anything important I’ll add to the bug report.

Thanks,
Chris