Ubuntu
linux-fsl-imx51 package

Slow Ethernet throughput and framing errors when connected via a hub

Bug #519905 reported by Dave Martin
10
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux-fsl-imx51 (Ubuntu)
Fix Released
Medium
Bryan Wu

Bug Description

Ubuntu lucid
linux-fsl-imx51 2.6.31.603.4 (and other versions)

Observed on Babbage 2.0 and Babbage 3.0

When connected to the network via a hub, TCP throughput will commonly drop down to ~100-200 kB/s, and NFS becomes sticky / unreliable, significantly impairing board usability.

When connected directly to a switch, full throughput is observed (~2-4 MB/s in our case)

This does not happen on Karmic (Babbage 2.0) or Jaunty (Babbage 1), and did not initially happen with lucid. The problem appeared to start when the 2.6.31 fsl kernel was merged (but I have no evidence for this now).

For now I'm assuming that this is an armel-specific issue, but since hubs are not in common use for most people, it could be more widespread.

Tags: armel
Revision history for this message
Paul Larson (pwlars) wrote :

Why kind of hub was this tested with? Has this been tested with more than one model of hub, or is it possible that it could be related to just that particular device?

Changed in linux-fsl-imx51 (Ubuntu):
assignee: nobody → Bryan Wu (cooloney)
importance: Undecided → Medium
Revision history for this message
Dave Martin (dave-martin-arm) wrote :

Only one model of hub has been tried (3Com OfficeConnect Dual Speed Hub 8 -- it's an 8-port 10/100Mbit hub), but we have tried with 3 of these and they all exhibit the same problem.

Boards running karmic and jaunty (and very early builds of lucid) communicate fine though these hubs, as does everything else we have connected to them. However, any imx51 board running a more recent lucid (Babbage 2.0 or 3) has the problem.

A direct cable connection to another host, or a connection to a switch does not have the problem.

Revision history for this message
Dave Martin (dave-martin-arm) wrote :

Bryan's test kernel with ethernet plug/unplug support looks like it may fix this issue!

See https://bugs.launchpad.net/ubuntu/+source/linux-fsl-imx51/+bug/457878/comments/8

Revision history for this message
Bryan Wu (cooloney) wrote :

Dave, Thanks for the testing.

The patch is already applied into our Lucid kernel. So I close this bug.

Changed in linux-fsl-imx51 (Ubuntu):
status: New → Fix Committed
Revision history for this message
Tobin Davis (gruemaster) wrote :

Marking as Fix Released as this is in the kernel now.

Changed in linux-fsl-imx51 (Ubuntu):
status: Fix Committed → Fix Released
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