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Author Topic: Abysmal network performance  (Read 3368 times)
plugger
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« on: June 07, 2009, 08:41:23 PM »

I have a brand new SheevaPlug running the default Ubuntu install (with root filesystem transferred to SDIO), plugged directly into a Netgear 802.11g router.

Network transfers to the plug from any machine on the local network are really slow, usually less than 1 MB/s. Everything is slow- FTP, HTTP, Samba, etc. Other machines on the network appear to be going at normal 802.11g speeds. Anyone have any ideas?

Everything works, and is still usable, just really slow. Sad
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dattaway
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« Reply #1 on: June 07, 2009, 08:48:08 PM »

QOS enabled on your router?  What does the routing table look like?  Try a tracepath?
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plugger
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« Reply #2 on: June 07, 2009, 11:09:49 PM »

The router is an old Netgear FWG114P 802.11g I've had for five years; it doesn't support QOS.

It resides at 192.168.0.1 and hands out DHCP addresses starting at 192.168.0.2 (to two laptops). The plug is at 192.168.0.8 which the router reserves for the plug's MAC. The plug is responding to pings with a latency between 1 and 8 ms. This is the routing table on the plug:

Kernel IP routing table
Destination      Gateway         Genmask            Flags Metric Ref    Use Iface
192.168.0.0     *                     255.255.255.0   U        0        0        0 eth0
default             192.168.0.1    0.0.0.0               UG     100     0        0 eth0


Meanwhile this is what the Netgear is reporting:
Destination            Mask                      Gateway               Metric  Active
default                   ---                          24.130.23.218      1          yes
24.130.20.0           255.255.252.0       24.130.23.218      1          yes
192.168.0.0           255.255.255.0       192.168.0.1          1          yes
192.168.0.1           255.255.255.255   192.168.0.1          1          yes
24.130.23.218       255.255.255.255   24.130.23.218      1          yes

And running tracepath locally on this laptop:

user@t60:~$  tracepath 192.168.0.8
  1:  t60.local            (192.168.232.135)  1.375ms pmtu 1500
  1:  192.168.232.2  (192.168.232.2)      0.280ms
  1:  192.168.232.2  (192.168.232.2)      0.252ms
  2:  192.168.0.8      (192.168.0.8 )         7.207ms reached
       Resume: pmtu 1500 hops 2 back 128
« Last Edit: June 07, 2009, 11:16:25 PM by plugger » Logged

plugger
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« Reply #3 on: June 11, 2009, 08:06:12 PM »

I searched around to figure out how to tune Linux networking parameters. Every HOWTO I find says you shouldn't mess with anything if TCP autotuning is set, which it is for kernels past 2.6.7, because then it's working perfectly:

root@debian:~# cat /proc/sys/net/ipv4/tcp_moderate_rcvbuf
1
root@debian:~# uname -a
Linux debian 2.6.22.18 #1 Thu Mar 19 14:46:22 IST 2009 armv5tejl GNU/Linux

So this is apparently as fast as it will go. No problems with any other machine on this LAN, just the plug. Is it a limitation of the harware? Are these plugs seriously going to run at 400 kb/sec with a 7 ms latency even on a 54Mbps LAN? I wish knew that when I bought one.
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MarkF
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« Reply #4 on: June 25, 2009, 07:05:56 AM »

Have you tried pinging through a hardwired connection instead of through that particular wireless router?

I get <1ms pings through a pair of Gbe switchs and a 10/100 switch.  Maybe the plug doesn't like your router? Undecided
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Mark

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« Reply #5 on: July 21, 2009, 07:28:14 PM »

I realize this is old, but it's worth a shot.

Some devices don't properly negotiate their speeds.  This can result in them accepting 10 instead of 100 or 1000 Mbps, and it can also result in them going half-duplex.  Does the collision light flash on your router? (If it's even visible -- many home internet gateways don't have this light.)  What do the stats on the Sheeva's ethernet device say?  Look for collisions, lost packets, retries, etc.  In fact, have you tried a different cable?  Stranger things have happened...
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Blexley
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« Reply #6 on: July 22, 2009, 01:59:57 AM »

some SheevaPlug Performance tests.


http://www.computingplugs.com/index.php/SheevaPlug_Performance

.
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birdman
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« Reply #7 on: July 22, 2009, 01:09:43 PM »

I have a brand new SheevaPlug running the default Ubuntu install (with root filesystem transferred to SDIO), plugged directly into a Netgear 802.11g router.
If it's plugged directly in why do you later mention "54Mbps LAN"?  That's a Wifi speed.  Are you referring to other clients?
Quote
Network transfers to the plug from any machine on the local network are really slow, usually less than 1 MB/s. Everything is slow- FTP, HTTP, Samba, etc. Other machines on the network appear to be going at normal 802.11g speeds. Anyone have any ideas?
..........
user@t60:~$  tracepath 192.168.0.8
  1:  t60.local            (192.168.232.135)  1.375ms pmtu 1500
  1:  192.168.232.2  (192.168.232.2)      0.280ms
  1:  192.168.232.2  (192.168.232.2)      0.252ms
  2:  192.168.0.8      (192.168.0.8 )         7.207ms reached
       Resume: pmtu 1500 hops 2 back 128

Where did that 192.168.232 network arrive from?  You haven't mentioned it anywhere!!
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