kern/125721: [ath] Terrible throughput/high ping latency with
Ubiquiti SR9/XR9
Geoffrey Mainland
mainland at eecs.harvard.edu
Thu Jul 17 16:40:01 UTC 2008
>Number: 125721
>Category: kern
>Synopsis: [ath] Terrible throughput/high ping latency with Ubiquiti SR9/XR9
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Thu Jul 17 16:40:01 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator: Geoffrey Mainland
>Release: 7.0-STABLE
>Organization:
Harvard University
>Environment:
FreeBSD citysense006 7.0-STABLE FreeBSD 7.0-STABLE #32: Fri Jul 11 19:21:09 UTC 2008 root at citybsd7.citysense.net:/usr/obj/usr/src/sys/CITYBSD i386
>Description:
I'm running 7-CURRENT on several ALIX 3c2 boards with SR9 radios and having
major performance problems: throughput on TCP streams generated by iperf often
falls to zero, and, depending on the HAL I use, I see ping latencies during one
of these iperf transfers of up to more than a *minute*. I've tried both the
0.9.30.13 HAL and the new 0.10.5.6 HAL. I see this bad behavior with both, but
the new HAL seems even worse.
I've documented my configuration and the test results at
http://www.eecs.harvard.edu/~mainland/freebsd/sr9/. This includes the kernel
configuration, dmesg output, pciconf output, rc.conf, statistics collected from
the ath driver, appropriate sysctl values, iperf/ping output generated by my
driver script and some plots showing the problem.
We are trying to deploy a bunch of these nodes outdoors, using the 900MHz radios
as a backhaul, so the drop-outs I see with SR9s are a major problem for us. I've
also run the same tests on Soekris nodes, used different SR9s, and also tried
the new XR9s on the same ALIX boards---all with similar results. We also have a
bunch of Wistrom CM9s which seem to work just fine.
Any idea what could be going on?
>How-To-Repeat:
I see this pattern of behavior with both XR9s and SR9s. It also happens on Soekris 4826 motherboards.
>Fix:
>Release-Note:
>Audit-Trail:
>Unformatted:
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