On 20 October 2011 05:35, Bryan Phillippe <b...@terran.org> wrote: > Hi All, > > After upgrading to compat-wireless-2011-10-10 and hostapd-0.7.3 on my > IXP4xx-based ARM Access Point, I'm seeing dramatically-improved stability and > performance. Great work! > > Under these combinations of software, I'm seeing long-term AP associations > maintained by the clients (no longer getting the drops and disconnects I was > seeing in previous versions); pretty good performance; and stable memory use. > > However, I've noted two issues that I'd like to explore with your help. The > first is that, under enough load, I still see this: > > ath: Failed to stop TX DMA!
Hm, that bug has been in FreeBSD/Linux for quite a while. I don't think we've ever figured out what it is, and it's likely some kind of magical cross-section of architecture, utilisation and NIC version. So, call it "hard to figure out." > This message doesn't really seem to coincide with a functional problem, so > perhaps I can just safely ignore it... Yeah, it's likely something to do with cabq traffic being disabled and being unable to. Don't worry about it for now. > The other problem I'm seeing is that when I have a lot of clients connected - > say, 20 or so - performance degrades pretty steeply and I start seeing high > packet loss. I know that sounds like a pure load issue, but I'd like to make > sure it's only that and not some efficiency setting I can tune in the driver. > I do NOT see this kind of performance degradation if I have the same 20 > people connected to the AP via a wired connection, doing the same traffic > test - so that seems to suggest the WiFi is suffering early. > > Thoughts or suggestions? Tests I can run? Data I can gather? Well, if you reach 20 people, there are a few questions: * are they saturating the air? is it something that can be fixed by driver hacking? * is it a tx or rx problem? or both? * have you hit some driver limit (eg ran out of crypto keycache slots and some clients are being done in software? or all? or an even worse failure mode?) ? I'd suggest grabbing some kind of diagnostic tool (eg wispy or something similar) and see how busy the spectrum is. The driver/mac80211 can give you some idea of how busy it sees the air being but I don't know whether the survey results are available in hostap mode. (iw survey, I think?) So the answer is "maybe, but you need to do further digging." Adrian _______________________________________________ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
