Bug 37622 - Poor wireless performance with Intel 4965AGN with iwl-legacy/iwl4965
Poor wireless performance with Intel 4965AGN with iwl-legacy/iwl4965
Status: CLOSED INSUFFICIENT_DATA
Product: Drivers
Classification: Unclassified
Component: network-wireless
All Linux
: P1 normal
Assigned To: Stanislaw Gruszka
:
Depends on:
Blocks: 32012
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Reported: 2011-06-16 11:22 UTC by MDstr_1
Modified: 2011-07-29 22:33 UTC (History)
4 users (show)

See Also:
Kernel Version: 2.6.39.1
Tree: Mainline
Regression: Yes


Attachments

Description MDstr_1 2011-06-16 11:22:52 UTC
Description: Prior to upgrade from kernel26-2.6.38, wireless performance was excellent I had a near none Invalid misc value and no Tx excessive retries from the output of iwconfig:

NOTE: I am connecting to this network via WPA2(AES)

wlan0 IEEE 802.11abgn ESSID:""
Mode:Managed Frequency:2.412 GHz Access Point:
Bit Rate=48 Mb/s Tx-Power=14 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:off
Link Quality=46/70 Signal level=-64 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:0 Invalid misc:194 Missed beacon:0

Post update to 2.6.39 there has been regression in bit rate performance and a large increase in errors :

output of iwconfig post 2.6.39 update:

wlan0 IEEE 802.11abgn ESSID:""
Mode:Managed Frequency:2.412 GHz Access Point:
Bit Rate=24 Mb/s Tx-Power=14 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:off
Link Quality=55/70 Signal level=-55 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:5 Invalid misc:33419 Missed beacon:0

output of dmesg |grep 4965 :

[ 5.842556] iwl4965: Intel(R) Wireless WiFi 4965 driver for Linux, in-tree:
[ 5.842578] iwl4965: Copyright(c) 2003-2011 Intel Corporation
[ 5.842580] Registering 4965 rate control operations
[ 5.842643] iwl4965 0000:03:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17
[ 5.842651] iwl4965 0000:03:00.0: setting latency timer to 64
[ 5.842678] iwl4965 0000:03:00.0: Detected Intel(R) Wireless WiFi Link 4965AGN, REV=0x4
[ 5.915174] iwl4965 0000:03:00.0: device EEPROM VER=0x36, CALIB=0x5
[ 5.915192] iwl4965 0000:03:00.0: Tunable channels: 11 802.11bg, 13 802.11a channels
[ 5.915451] iwl4965 0000:03:00.0: irq 48 for MSI/MSI-X
[ 6.017997] iwl4965 0000:03:00.0: loaded firmware version 228.61.2.24
[ 6.401528] ieee80211 phy0: Selected rate control algorithm 'iwl-4965-rs'



output of lspci | grep 4965 :
03:00.0 Network controller: Intel Corporation PRO/Wireless 4965 AG or AGN [Kedron] Network Connection (rev 61)

excerpt from output of lsmod in 2.6.39:
mac80211 211822 2 iwl4965,iwl_legacy

At times the wireless functionality is nearly unusuable in 2.6.39.
I can confirm that since downgrading back to 2.6.38 on Arch that the wireless functionality is fine.

I noticed iwlcore was depreciated and driver support for this hardware was moved to iwl-legacy from iwlagn... maybe changes with this has something to do with it?

-MDstr
Comment 1 Stanislaw Gruszka 2011-06-16 16:40:35 UTC
Try these two patches (queued to 2.6.39.2). One of them should help.
http://article.gmane.org/gmane.linux.kernel.stable/13224
http://article.gmane.org/gmane.linux.kernel.stable/13255
Comment 2 Stanislaw Gruszka 2011-07-18 11:11:38 UTC
Patches are already applied in 2.6.39.2 kernel. Does update to it or newer 2.6.39.x kernel solve the problem?

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