WiFi performance

Petter Adsen petter at synth.no
Fri Jun 26 13:02:50 UTC 2015


On Sat, 20 Jun 2015 16:34:06 +0200
Liam Proven <lproven at gmail.com> wrote:

> On 20 June 2015 at 08:58, Petter Adsen <petter at synth.no> wrote:
> > lspci gives me this on the WiFi interface:
> > 02:00.0 Network controller: Intel Corporation Centrino Wireless-N 1000 [Condor Peak]
> >
> > The problem is that I'm getting absolutely abysmal performance. The
> > router it's connected to is a TP-Link Archer C5 running OpenWRT, and
> > according to the OpenWRT webui, it opens a connection with a bitrate of
> > 150Mbps.
> >
> > On average, I get about 2Mbps when downloading or copying files over
> > NFS. Running iperf3, I get an average of 11Mbps over TCP, and 27Mbps
> > over UDP. This is from another vivid box, connected to the router via
> > gigabit Ethernet.
> >
> > Any suggestions on things I could try to get better performance, apart
> > from replacing the WiFi card?
> 
> 
> First steps in isolating the problem:
> 
> [1] Try on a different WLAN

Don't have access to one, unfortunately. But other wireless clients
don't seem to have this problem.

> [2] Try with a cable.

Network performance is quite normal on a wired network.

I've been digging a little more into this, with odd results. iperf3
gives me this over TCP (cut for brevity):

[  4]   9.00-10.00  sec  1.17 MBytes  9.85 Mbits/sec    0   24.0 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-10.00  sec  11.1 MBytes  9.30 Mbits/sec    0             sender
[  4]   0.00-10.00  sec  11.1 MBytes  9.27 Mbits/sec                  receiver

A few suggestions I found online included disabling power management
and 802.11n, both of which I've tried, and now get:

[  4]   9.00-10.00  sec  2.60 MBytes  21.8 Mbits/sec    0   31.1 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval           Transfer     Bandwidth       Retr
[  4]   0.00-10.00  sec  25.7 MBytes  21.5 Mbits/sec    0             sender
[  4]   0.00-10.00  sec  25.6 MBytes  21.5 Mbits/sec                  receiver

From "iwconfig wlan0" I get this:

          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:186   Missed beacon:0

The "Invalid misc" number increases quite rapidly, could this be the
source of the problem? Where should I continue digging?

Any advice on what to examine would be most helpful.

Petter

-- 
"I'm ionized"
"Are you sure?"
"I'm positive."
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