Bug 753299

Summary:	[iwl3945] permanent speed drop to 100kBps
Product:	[Fedora] Fedora	Reporter:	Maciek Borzecki <maciek.borzecki>
Component:	kernel	Assignee:	Stanislaw Gruszka <sgruszka>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	16	CC:	amessina, gansalmon, itamar, jonathan, kernel-maint, madhu.chinakonda, sgruszka
Target Milestone:	---
Target Release:	---
Hardware:	i686
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2012-02-07 15:00:33 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:

Description Maciek Borzecki 2011-11-11 20:25:51 UTC

Description of problem:
The DL throughput of a wireless interface is limited to 100kB/s. This happens after running traffic for some time (torrent linke, a lot of uplink/downlink connections, possibly saturating the wireless link).
Once the speed gets capped at 100kB/s, reassociation or bringing the link down and up helps to recover full speed. 
If iwl3945 is loaded with disable_hw_scan=0, the problem does occur. Possibly due to another bug in card's firmware/driver which causes the card firmware to be reset every 2 minutes.
The problem was never visible on F14.

I looks as if there is some smart policing employed on DL at the MAC level.

I tried running with wireless compat rebuild with srpms from compat wireless repo maintained by sgruszka, but that failed miserably with a kernel panic when loading mac80211.

Version-Release number of selected component (if applicable):
kernel-3.1.0-7.fc16.i686
iwl3945-firmware-15.32.2.9-5.fc15.noarch

How reproducible:
Always

Steps to Reproduce:
1. Start running traffic through the wireless interface
2. Wait
3. Behold speed cap
  
Actual results:
DL throughput capped at 100kB/s

Expected results:
Full DL throughput available.

Additional info:

Smolt profile - http://www.smolts.org/client/show/pub_e280de94-21ab-4973-80c0-828bdf969de6

Comment 1 Stanislaw Gruszka 2011-11-14 14:42:04 UTC

I plan to do some serious iwlegacy driver rewrite/clean-up hoping that would help to various issues we have with this driver including that one.

For now you may try to disable periodic scanning in NetworkManager, you have to edit connections, choose wireless and then your SSID (wireless network) name, then click Edit and insert your AP MAC address into BSSID: field. With constant AP BSSID NetworkManager will do not want to search APs for roaming, hence do not perform scanning while associated.

Comment 2 Stanislaw Gruszka 2012-01-18 11:47:52 UTC

Current upstream version include various iwlegacy changes. Micorocode error during periodic scan with disable_hw_scan=0 should be fixed. Not sure about slow speed problem. Please test. You can use my compat-wireless-next rpm's, I updated them yesterday. Remember to reboot system after installing the package, otherwise there could be mishmash with mac80211 versions, what most likely was reason of crash in mac80211 you reported in comment 0.

Comment 3 Stanislaw Gruszka 2012-02-02 13:25:41 UTC

Any feedback here? Latest fedora 14 kernel 3.2.2 include build-in compat-wireless-3.3-rc1 package, can you test that?

Comment 4 Maciek Borzecki 2012-02-05 06:44:40 UTC

I've been running kernel-3.2.2-1.fc16.i686 on F16 for a couple of days now, and didn't notice any slowdowns yet. Should the problem appear again, I'll report back

Comment 5 Stanislaw Gruszka 2012-02-07 15:00:33 UTC

Ok, I'm closing bug for now, just reopen if problem will happen again.