#7552: bcm47xx/b43 wireless connection suddenly stops when router system load
increases
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Reporter: amain@… | Owner: hauke
Type: defect | Status: closed
Priority: response- | Milestone:
needed | Version: Backfire 10.03
Component: base | Keywords: b43 hostapd link stability system
system | load
Resolution: fixed |
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Comment (by pfalcon):
Thanks for clarification regarding patch being merged to upstream, that's
good news.
And I'd like to share my experiences with this issue. First of all, for
me, issue is very easy reproducible in following way: I have NAS connected
to router (WL-500gD) via wired Ethernet, and whenever I try to download
something sizable on NAS (which thus goes to router via Ethernet, which
then does NAT on it, and routes to ISP connection, via Ethernet too), I
very soon experience WiFi connection drop. To clarify again: yes,
overloading Ethernet connection causes WiFi going down. Experimenting,
this happens when download speed is higher than ~1.3Mbyte/s. CPU load and
loadavg is high when this happens, so I'm sure this is the same issue as
described in this ticket - fast coming ethernet packets take quite an
effort from CPU to do masquerading, which causes b43 interrupts to be
delayed/missed, which causes WiFi going down.
When I decided to investigated this, I had 12.09 installed, I downgraded
to 10.03.1 (2.6 kernel), just to find out that situation is worse, as wifi
connection doesn't recover automatically (well, in full correspondence
with this ticket's timeline). After I found this ticket, I upgraded to
trunk daily build: "BARRIER BREAKER (Bleeding Edge, r41302)", which, based
on the discussion above, should have all the fixes.
Unfortunately, I cannot say that issue, as formulated above, resolved.
Maybe, maybe it takes a bit longer from download start until the wifi
connection drops, but that's the only effect I can see, which is hard to
quantify and may be a placebo effect. Trying to download anything CD-size
(like a movie) causes wifi connection drop not later than in a minute. And
immediately after starting ethernet download, wifi connection is
effectively blocked - no web page can be opened for example (though pings
leisurely get thru). It all ends in wifi disconnect soon, and then
connection is not re-established until download on NAS finishes.
Precompiled builds from http://downloads.openwrt.org/snapshots/trunk/
don't have any debug files mentioned above, so I cannot provide more
specific info regarding what happens when connection drops. I hoped to be
able to build my own image, but couldn't get to it 3 weeks now, so decided
to just write down the above, in case someone may be interested.
--
Ticket URL: <https://dev.openwrt.org/ticket/7552#comment:133>
OpenWrt <http://openwrt.org>
Opensource Wireless Router Technology
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