Date: Wed, 6 Sep 2017 18:30:25 -0400 From: Chris Gordon <freebsd@theory14.net> To: Russell Haley <russ.haley@gmail.com> Cc: freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: Beaglebone Black + FreeBSD + USB WiFi = WAP? Message-ID: <E1992F2B-236D-467C-AAEE-B81A59EB1138@theory14.net> In-Reply-To: <CABx9NuQtXRbN6YPihotuLSnE5cFG-xvRRNYyFSLGxZNPBnKTKQ@mail.gmail.com> References: <40EA308E-489D-4A0B-B75A-2CA5A4EC474E@theory14.net> <685d0eed3532a34f239e7ff893f817db@bakulin.de> <EB1907C8-7A0A-4D45-AD21-B449DC4C0D7D@theory14.net> <CABx9NuQCrspSzcdXh0_cbO1QmexwQbrk1djaGyvKTp370AtxYA@mail.gmail.com> <CABx9NuQJWot9xgs1QtzJ87NfgZM=FPhZ%2B2a-RewDonvGG5LLKg@mail.gmail.com> <CABx9NuT1n8ZYPrZTB8vT2sBmT3U75E4UFgAGA3ZOPTotpsUWeg@mail.gmail.com> <CABx9NuQB=xBNt6%2BX=YKw4XVW5u1XysW%2Bo7pqO_9D2RC%2BF6bKug@mail.gmail.com> <20170905141711.6545490.14963.31294@gmail.com> <656A5193-7389-476C-AF58-EB013E9155F3@theory14.net> <CABx9NuQtXRbN6YPihotuLSnE5cFG-xvRRNYyFSLGxZNPBnKTKQ@mail.gmail.com>
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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=E2=80=9D 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=E2=80=99t be until next week when I can look at any of these. = I=E2=80=99m one of the organizers at vBSDcon and will be at the Dev = Summit and conference through the weekend. If anyone is interested, = I=E2=80=99m 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=E2=80=99ll get some info as soon as I can. = Anything important I=E2=80=99ll add to the bug report. Thanks, Chris
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