Bug 42952

Summary:	iwlwifi drops out under load
Product:	Drivers	Reporter:	Martin Pool (mbp)
Component:	network-wireless	Assignee:	drivers_network-wireless (drivers_network-wireless)
Status:	CLOSED OBSOLETE
Severity:	normal	CC:	eike.thaden, ilw, linville, pier-luc
Priority:	P1
Hardware:	All
OS:	Linux
URL:	https://bugs.launchpad.net/ubuntu/+source/linux/+bug/956732
Kernel Version:	3.3.0-030300rc7	Subsystem:
Regression:	No	Bisected commit-id:
Attachments:	dmesg lspci -vvv

Description Martin Pool 2012-03-17 22:39:57 UTC

(originally reported in https://bugs.launchpad.net/ubuntu/+source/linux/+bug/956732)

On a Thinkpad x201, on today's Precise, with upstream kernel 3.3.0-030300rc7-generic

wifi works reliably in general, but under load (~2Mbps) it will fail: receiving no traffic, but not giving any obvious errors

To produce enough load, I started downloading several Ubuntu ISOs from remote servers. This works for a variable period of time, sometimes a few minutes, topping out at 2MB/s, which is about my ADSL peak speed.

At moderate load it can work all day, including across suspend/resume cycles, so at least the symptoms are different to bug 948235 and bug 956401, though perhaps the cause is the same.

Running 'sudo rmmod iwlwifi && sudo modprobe iwlwifi' consistently gets it working again.

I'm happy to help debug or test this is someone gives me a suggestion.

Comment 1 Martin Pool 2012-03-17 23:40:50 UTC

... that should have said 2MByte/s, not Mbit

Comment 2 Pier-Luc Théberge 2012-05-27 17:52:33 UTC

That issue happens to me consistently when using MythTV to stream video content at 16-18mbits.  It takes approximately 1 minute for the signal to drop.

As Martin Pool mentioned, unloading/reloading the iwlwifi module does the job, using the hardware switch does too.

Any way I can help debugging or testing?

Comment 3 Pier-Luc Théberge 2012-05-27 17:53:11 UTC

I forgot mentionning it also happens to me on kernels 3.2 and 3.4 series.

Comment 4 Eike Thaden 2012-06-07 13:50:41 UTC

I regularly (~ 1-3 times per hour) experience the same issue. I'm using ubuntu 12.04 AMD64 with the Ubuntu kernel 3.2.0-25-generic. Sometimes the drop-out is accompanied with a dmesg message "Microcode SW error detected.  Restarting 0x2000000." (see attachments for details), but not always.

Switching wireless off and on again allows for successful reconnection.

Comment 5 Eike Thaden 2012-06-07 13:51:16 UTC

Created attachment 73525 [details]
dmesg

Comment 6 Eike Thaden 2012-06-07 13:51:45 UTC

Created attachment 73526 [details]
lspci -vvv

Comment 7 Emmanuel Grumbach 2014-03-19 12:00:37 UTC

still an issue?