Bug 78341

Summary:	[iwlwifi] Low throughput on Centrino 6250
Product:	Drivers	Reporter:	ValdikSS (iam)
Component:	network-wireless	Assignee:	drivers_network-wireless (drivers_network-wireless)
Status:	CLOSED DOCUMENTED
Severity:	normal	CC:	ilw, linville
Priority:	P1
Hardware:	x86-64
OS:	Linux
Kernel Version:	3.15.1	Subsystem:
Regression:	No	Bisected commit-id:

Description ValdikSS 2014-06-19 09:34:50 UTC

Hello.
It seems that I always had wireless speed issue with my Intel Centrino 6250 adapter in Linux. I had a pretty cheap AP without MIMO and I thought that's AP issue, but now I have TP-Link TL-WDR4300 with 3x3 MIMO and I here are the results:

Tested with wget --no-passive-ftp -O /dev/null 'ftp://192.168.5.10/Anime/AIR/\[uguu~\]_AIR_01v3_\(BD-1080p\)_\[976D39A4\].mkv' --report-speed=bits

Linux, 2.4GHz. Link speed 130-144 MBit/s, wget result: ~40 MBit/s
Linux, 5GHz. Link speed 270-300 MBit/s, wget result: 49-53 MBit/s

Windows, 2.4GHz. Link speed 130 MBit/s, wget result: 48-52 MBit/s
Windows, 5Ghz. Link speed 300MBit/s, wget result: 72-88 MBit/s

03:00.0 Network controller [0280]: Intel Corporation Centrino Advanced-N + WiMAX 6250 [Kilmer Peak] [8086:0089] (rev 35)
Lenovo X220
192.168.5.10 is connected to LAN port so no NAT is involved.

Comment 1 Emmanuel Grumbach 2014-06-24 07:43:22 UTC

please try 11n_disable=8

Comment 2 ValdikSS 2014-06-24 08:26:39 UTC

(In reply to Emmanuel Grumbach from comment #1)
> please try 11n_disable=8

Thanks, that helped. Are there any problems with this option so it's not enabled by default?
Found this https://lkml.org/lkml/2014/4/1/266
My NIC is supported by iwldwm, and with 11n_disable=8 it seems to work much faster (as in Windows). Should I expect stability issues?

Comment 3 Emmanuel Grumbach 2014-06-24 09:28:30 UTC

Yes - we've had issues with this feature. So I disabled it by default because few people really need throughput and most users need stability.