Arch Linux

herr_tichy

Member

Registered: 2014-04-23

Posts: 2

high latency with Intel AC 7260

Hi forum,

I've just installed Arch on my new Thinkpad T540p. WLAN connectivity at 5GHz as well as 2.4GHz is suboptimal.

pinging my router:

$ ping 192.168.2.1
PING 192.168.2.1 (192.168.2.1) 56(84) bytes of data.
64 bytes from 192.168.2.1: icmp_seq=1 ttl=64 time=17.1 ms
64 bytes from 192.168.2.1: icmp_seq=2 ttl=64 time=39.4 ms
64 bytes from 192.168.2.1: icmp_seq=3 ttl=64 time=61.1 ms
64 bytes from 192.168.2.1: icmp_seq=4 ttl=64 time=83.5 ms
64 bytes from 192.168.2.1: icmp_seq=5 ttl=64 time=105 ms
64 bytes from 192.168.2.1: icmp_seq=6 ttl=64 time=24.9 ms

Immediately after reconnecting to the AP, latencies look good and then get worse:

64 bytes from 192.168.2.1: icmp_seq=26 ttl=64 time=1.97 ms
64 bytes from 192.168.2.1: icmp_seq=27 ttl=64 time=1.83 ms
64 bytes from 192.168.2.1: icmp_seq=28 ttl=64 time=1.77 ms
64 bytes from 192.168.2.1: icmp_seq=29 ttl=64 time=1.80 ms
64 bytes from 192.168.2.1: icmp_seq=30 ttl=64 time=1.99 ms
64 bytes from 192.168.2.1: icmp_seq=31 ttl=64 time=196 ms
64 bytes from 192.168.2.1: icmp_seq=32 ttl=64 time=13.7 ms
64 bytes from 192.168.2.1: icmp_seq=33 ttl=64 time=35.2 ms
64 bytes from 192.168.2.1: icmp_seq=34 ttl=64 time=57.2 ms
64 bytes from 192.168.2.1: icmp_seq=35 ttl=64 time=79.5 ms
64 bytes from 192.168.2.1: icmp_seq=36 ttl=64 time=101 ms
64 bytes from 192.168.2.1: icmp_seq=37 ttl=64 time=21.0 ms
64 bytes from 192.168.2.1: icmp_seq=38 ttl=64 time=43.2 ms
64 bytes from 192.168.2.1: icmp_seq=39 ttl=64 time=65.4 ms

Creating traffic on the network actually reduces lag.

64 bytes from 192.168.2.1: icmp_seq=18 ttl=64 time=118 ms
64 bytes from 192.168.2.1: icmp_seq=19 ttl=64 time=33.2 ms
64 bytes from 192.168.2.1: icmp_seq=20 ttl=64 time=61.0 ms
64 bytes from 192.168.2.1: icmp_seq=21 ttl=64 time=78.8 ms
64 bytes from 192.168.2.1: icmp_seq=22 ttl=64 time=106 ms

--- starting iperf client ---

64 bytes from 192.168.2.1: icmp_seq=23 ttl=64 time=22.2 ms
64 bytes from 192.168.2.1: icmp_seq=24 ttl=64 time=18.8 ms
64 bytes from 192.168.2.1: icmp_seq=25 ttl=64 time=16.2 ms
64 bytes from 192.168.2.1: icmp_seq=26 ttl=64 time=18.5 ms
64 bytes from 192.168.2.1: icmp_seq=27 ttl=64 time=18.7 ms
64 bytes from 192.168.2.1: icmp_seq=28 ttl=64 time=16.7 ms
64 bytes from 192.168.2.1: icmp_seq=29 ttl=64 time=15.5 ms
64 bytes from 192.168.2.1: icmp_seq=30 ttl=64 time=16.5 ms
64 bytes from 192.168.2.1: icmp_seq=31 ttl=64 time=17.9 ms
64 bytes from 192.168.2.1: icmp_seq=32 ttl=64 time=19.8 ms
64 bytes from 192.168.2.1: icmp_seq=33 ttl=64 time=15.6 ms

--- iperf run finished ---

64 bytes from 192.168.2.1: icmp_seq=34 ttl=64 time=68.8 ms
64 bytes from 192.168.2.1: icmp_seq=35 ttl=64 time=88.4 ms
64 bytes from 192.168.2.1: icmp_seq=36 ttl=64 time=114 ms

[    2.298710] iwlwifi 0000:04:00.0: irq 44 for MSI/MSI-X
[    2.308879] iwlwifi 0000:04:00.0: loaded firmware version 22.24.8.0 op_mode iwlmvm
[    2.325958] iwlwifi 0000:04:00.0: Detected Intel(R) Dual Band Wireless AC 7260, REV=0x144
[    2.326041] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S
[    2.326395] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S
[    2.505219] ieee80211 phy0: Selected rate control algorithm 'iwl-mvm-rs'
[    3.864572] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S
[    3.864910] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S

I assume that the wlan adapter enters into some kind of sleep mode when there's not much traffic. How can I change this?

herr_tichy

Member

Registered: 2014-04-23

Posts: 2

Re: high latency with Intel AC 7260

I solved it somewhat. linux-firmware brings the two latest versions of the firmware. I removed the newer version (iwlwifi-7260-8.ucode) from /usr/lib/firmware and now it loads the older one:

[    3.963557] iwlwifi 0000:04:00.0: irq 44 for MSI/MSI-X
[    3.967186] iwlwifi 0000:04:00.0: loaded firmware version 22.1.7.0 op_mode iwlmvm
[    3.985443] iwlwifi 0000:04:00.0: Detected Intel(R) Dual Band Wireless AC 7260, REV=0x144
[    3.985505] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S
[    3.985732] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S
[    4.183730] ieee80211 phy0: Selected rate control algorithm 'iwl-mvm-rs'
[    4.870899] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S
[    4.871175] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S

Now everything works. Oh well.

Hantabaru

Member

Registered: 2009-02-25

Posts: 58

Re: high latency with Intel AC 7260

I solved it somewhat. linux-firmware brings the two latest versions of the firmware. I removed the newer version (iwlwifi-7260-8.ucode) from /usr/lib/firmware and now it loads the older one:

[    3.963557] iwlwifi 0000:04:00.0: irq 44 for MSI/MSI-X
[    3.967186] iwlwifi 0000:04:00.0: loaded firmware version 22.1.7.0 op_mode iwlmvm
[    3.985443] iwlwifi 0000:04:00.0: Detected Intel(R) Dual Band Wireless AC 7260, REV=0x144
[    3.985505] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S
[    3.985732] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S
[    4.183730] ieee80211 phy0: Selected rate control algorithm 'iwl-mvm-rs'
[    4.870899] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S
[    4.871175] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S

Now everything works. Oh well.

Hi herr_tichy

Just to give some extra info to others having problems with this wireless adapter

I have the same wireless adapter in my Thinkpad T440p and by renaming the newest firmware so the older one loaded, I got a jump in signal quality from around 49% to around 94% !

(I had also disabled the power saving on the adapter before renaming the driver, in case this was affecting the signal quality).

Will just have to hope Intel fixes this in the next firmware update...

petre

Member

Registered: 2014-06-03

Posts: 1

Re: high latency with Intel AC 7260

Hi all,
Reverting to an older firmware makes indeed the wireless connection better, but the sound via bluethoot will have a latency of 1-2 seconds. Are we sure Intel knows about this issues?

Cheers,
Petre

muz

Member

Registered: 2009-01-21

Posts: 17

Re: high latency with Intel AC 7260

Hello Patre,

I can confirm your bluetooth issues on a Vaio Pro with an intel 7260. Now, how do we make sure intel knows about this?

Murat