Date: Fri, 10 Jul 2009 20:38:51 +0200 From: Marten Vijn <info@martenvijn.nl> To: Sam Leffler <sam@freebsd.org> Cc: mobile@freebsd.org Subject: Re: ath0 / wlan0 on 8.0 Message-ID: <1247251131.5235.147.camel@mvn-desktop> In-Reply-To: <4A5601CB.3060809@freebsd.org> References: <1247090347.10461.7.camel@mvn-desktop> <4A5601CB.3060809@freebsd.org>
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On Thu, 2009-07-09 at 07:42 -0700, Sam Leffler wrote: > Marten Vijn wrote: > > hi all, > > > > When benchmarkmarking an ath0 card an I get these errors. > > After a could (~10) no traffic is possible anymore. > > > > "no traffic is possible" doesn't say enough. Retested for beta-1 - ping does not respond any more. - the client loses associations. see: http://www.youtube.com/watch?v=sfE-YskT7XM for a screen cast > Do you see beacons from the ap? - I still see beacon frames > Are interrupts being received on the ap? Are you out of > resources like mbufs? What are the command to produce this information? > I have seen, for example, things like nightly > cron scripts accidentally left to run and kill operation. Not very likey, It an NET4826, just rebooted, this very reproducable it 1 or 2 test runs. > > > What does this message mean? > > > > ath0: stuck beacon; resetting (bmiss count 4) > > ath0: stuck beacon; resetting (bmiss count 4) > > ath0: stuck beacon; resetting (bmiss count 4) > > > > It means 4 consecutive beacon intervals went by w/o the ap being able to > xmit a beacon frame. When this happens the driver does a h/w reset of > the chip and continues. You can raise this threshold but if it's > happening a lot you should understand why. To much traffic that leads to a dos. I am aware that I create a lot of traffic. That's why it is benchmark. > > > > # uname -a > > FreeBSD 8.0-CURRENT FreeBSD 8.0-CURRENT #0: Mon Jun 29 21:44:19 CEST > > 2009 root@master:/usr/obj/nanobsd.node_ap_64M/usr/src/sys/KERNEL > > i386 > > # > > > > > The only 8.0 log under "crashes" does not point to a system crash. > > I didn't see information on the wireless setup (e.g. ifconfig commands > to setup and/or status to show final operating syste). Does this happen > on all channels? What else is running on the machine with the ap? What > is the network traffic mix (e.g. tx vs rx)? I created a new report for 8.0.beta-1 on the site with more info: http://bsd.wifisoft.org/trac/wiki/crash4 all (UDP) traffic created on the clients and flows to the server (one jail per client) > I know several groups using the Alix board in similar configs to run > production ap's with >10 users but you will need to tune the system for > best operation. I had 50~60 users concurrent on ap's on ApacheCon Amsterdam in spring. Ap's did fail every couple of hours/days. That workable for 10 ap's, but not for > 100. > Under extreme wireless network load the PCI bus becomes > a bottleneck and causes the host to be unable to setup each beacon frame > in real-time to satisfy NextTBTT requirements. > Look at how the SWBA mechanism works in the driver and the hw.ath.hal.sw_brt and > hw.ath.hal.dma_brt tunables. Could you give my pointers for documentation/stuff to read? (it will take me some time to read and maybe understand it. my background not technical) > Otherwise stuck beacon conditions can be caused by the ap not getting > access to the wireless medium due to it being busy. You should sniff > traffic around the time of a problem for clues. There are also h/w > registers you can observe (e.g. with athregs) to see how busy the medium > is from the POV of the ap. There have been chip bugs related to this > condition but doing a reset should always restore operation. > If this > isn't happening should be able to diagnose what's going with the > existing facilities (e.g. athdebug msgs). nice! I will rebuild the nanobsd img's to use /usr/src/tools/tools/ath/* > Understand however that building a product ap is nontrivial and the FreeBSD ath driver can > easily be optimized better for this purpose. I am not building a product, I am using FreeBSD wifi / networking env and as show case of working Opensource Software. IHMO the benchmarking could help harden to wlan drivers and FreeBSD based accesspoints. I expect to double the clients in the benchmark in the coming weeks. Then I will do more testing. Please let know how I can support to create usable (debug) output. thanks for your reply, Marten > > Sam > -- http://martenvijn.nl Marten Vijn http://martenvijn.nl/trac/wiki/soas Sugar on a Stick http://bsd.wifisoft.org/nek/ The Network Event Kit http://har2009.org 13th-16th August http://opencommunitycamp.org 26th Jul - 2nd August
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