[NBLUG/talk] Extremely poor network performance

Aaron Grattafiori nite at sonic.net
Mon Mar 27 20:40:53 PST 2006


Lincoln Peters wrote:

> I have one box running Debian/testing on my network that has been
> demonstrating hideously poor performance on my Ethernet LAN.  I tried
> uploading a large directory to it via scp, and the throughput for each
> file rarely exceeds 10KB/s.  There is also a delay of several seconds
> between when one file finishes uploading and another begins.  At this
> rate, it will take several weeks to upload a 35GB directory on a
> 100BaseTX LAN!
>
>
> Two days ago, I tried pinging the misbehaving Linux box (60 pings
> total, at 1 ping per second) from the machine I was trying to upload
> from (a Macintosh running MacOS 10.4.5).  The results were:
>
> round-trip min/avg/max/stdev = 0.507/285.772/911.228/233.467 ms
>
>
> I had heard that this particular type of Macintosh had been reported
> to have issues with network performance, so at first I suspected it
> was having problems.  So I tried pinging two other Linux boxes from
> the Macintosh:
>
> round-trip min/avg/max/stdev = 0.377/0.456/0.671/0.046 ms
> round-trip min/avg/max/stdev = 0.451/0.624/0.934/0.060 ms
>
> So apparently, the problem was NOT on the Mac's end.
>
>
> I didn't have time to invesigate further that day, so the next day, I
> went to the misbehaving box and tried pinging two other Linux boxes on
> the LAN:
>
> rtt min/avg/max/mdev = 0.240/548.421/1817.558/499.307 ms, pipe 2
> rtt min/avg/max/mdev = 0.146/408.204/1478.301/358.105 ms, pipe 2
>
>
> Then I tried pinging the misbehaving box from the Macintosh again, and
> the results were even worse:
>
> round-trip min/avg/max/stdev = 0.433/1512.158/5762.936/1319.562 ms
>
>
> As far as I could tell, there is virtually no other traffic going in
> or out of the computer that would explain these wildly varying
> response times.  But just to be sure, I disabled every server program
> that might have beeen generating network traffic.  This morning, I
> tried using the misbehaving box to ping another Linux box:
>
> rtt min/avg/max/mdev = 0.151/4980.819/21034.876/4896.826 ms, pipe 10
>
>
> Then I tried pinging my mail server (which is on the Internet, and
> therefore accessed via my router), and the results were almost shocking:
>
> 60 packets transmitted, 53 received, 11% packet loss, time 1058068ms
> rtt min/avg/max/mdev = 60.530/4647.363/22086.280/4880.662 ms, pipe 13
>
> (I indicate packet loss here because this is the only test I ran that
> experienced any packet loss.)
>
> To make things even stranger, there was a huge lag between the
> transmission of each ping.  Although I had indicated that a total of
> 60 pings should be sent out at 1-second intervals, the entire
> operation (according to the "time" command) took 18 minutes, 37.984
> seconds!
>
>
> To be thorough, I tried using the Macintosh to ping the same mail server:
>
> 60 packets transmitted, 60 packets received, 0% packet loss
> round-trip min/avg/max/stdev = 60.243/62.168/65.857/1.105 ms
>
>
> Finally, I tried restarting the network connection on this computer
> (as per "ifdown" and "ifup").  Now it seems to be fine, but I can't
> figure out why.  Seeing as how this computer is running Linux and
> therefore should not be subject to random failures, I worry that the
> problem will come up again, that and it might even get worse over time.
>
> Any ideas what might be going on?
>
>
I know that on my FreeBSD server, I have some crappy no-name NIC card in
it.. and if im transferring a lot of files it will go really fast, then
kinda stall and die (it goes into store and forward says dmesg). So..
check your logs.. then you might try switching network cards or something.
Process of elimiation is probably the "default route" (haha). I highly
doubt it has anything to do with the OS.

Good luck!
 -Aaron



More information about the talk mailing list