Hi,
I have two identical Dell Inspiron 530n desktops running latest w-t
(07e789c5094735747b3df8a7840f61467575ba9e, master 2011-05-04) on
Ubuntu 10.04.2 LTS. I have uninstalled network-manager from both
devices and, as far as I can tell, no software processes or daemons
interfere with my wireless configurations.
The AP machine has an AR9280-based device and an IWL5300 based device.
I blacklist ath9k and iwlagn modules from loading on boot. It is
running latest hostap.git, though I've seen the same issue with older
versions.
The client machine has one AR9380-based NIC, one IWL5300-based NIC,
and one RT2800pci NIC. I blacklist ath9k, iwlagn, and rt2800pci from
loading on boot.
When I set up the client to connect (using iwconfig essid) to the AP
(no encryption, channel 48 with HT40-) and run iperf, I sometimes see
2-second drops of the connection. I run iperf to generate elastic TCP
flows that see ~150 Mbps, and in parallel I run ping <AP> -i 0.2.
Here's the ping log:
64 bytes from 192.168.1.2: icmp_seq=622 ttl=64 time=107 ms
64 bytes from 192.168.1.2: icmp_seq=623 ttl=64 time=117 ms
64 bytes from 192.168.1.2: icmp_seq=624 ttl=64 time=125 ms
64 bytes from 192.168.1.2: icmp_seq=625 ttl=64 time=2152 ms
64 bytes from 192.168.1.2: icmp_seq=626 ttl=64 time=1989 ms
64 bytes from 192.168.1.2: icmp_seq=627 ttl=64 time=1779 ms
64 bytes from 192.168.1.2: icmp_seq=628 ttl=64 time=1570 ms
64 bytes from 192.168.1.2: icmp_seq=629 ttl=64 time=1360 ms
64 bytes from 192.168.1.2: icmp_seq=630 ttl=64 time=1150 ms
64 bytes from 192.168.1.2: icmp_seq=631 ttl=64 time=950 ms
64 bytes from 192.168.1.2: icmp_seq=632 ttl=64 time=750 ms
64 bytes from 192.168.1.2: icmp_seq=633 ttl=64 time=550 ms
64 bytes from 192.168.1.2: icmp_seq=634 ttl=64 time=340 ms
64 bytes from 192.168.1.2: icmp_seq=635 ttl=64 time=130 ms
64 bytes from 192.168.1.2: icmp_seq=636 ttl=64 time=2.73 ms
64 bytes from 192.168.1.2: icmp_seq=637 ttl=64 time=1.18 ms
64 bytes from 192.168.1.2: icmp_seq=638 ttl=64 time=1.18 ms
64 bytes from 192.168.1.2: icmp_seq=639 ttl=64 time=1.18 ms
64 bytes from 192.168.1.2: icmp_seq=640 ttl=64 time=1.18 ms
you can see that ping times are large while the TCP flow is active,
but drop to about 1.18ms after it stops. You can also clearly see the
pings get backed-up for 2 seconds and then release. This tends to
happen in the last 5 seconds of a 30s TCP flow, which starts almost
immediately after association. I wonder if it might be related to some
event that may get triggered 30s after association in either hostap or
mac80211 or ath9k.
This is reproducible (albeit infrequently) with the stock w-t kernel;
I've also generated a version of the code in which I print out
messages (KERN_INFO priority) inside of minstrel_ht whenever get_rate
is called and whenever tx_status is called. I verified that there is
**NO LOSS** measured by either side. Also, the gap in the messages is
nearly exactly 2 seconds long, e.g., 2.03 seconds.
Any thoughts as to what could be causing this?
A final, but probably wrong, note. This seems to be (qualitatively)
harder to reproduce if I don't compile in rt2800pci support. But, I
blacklist the modules and I've verified that none of them are loaded
on boot, so I don't know why this would be a problem.
Thanks,
Dan
On Wed, May 4, 2011 at 6:50 PM, Sujith <[email protected]> wrote:
> Sujith wrote:
>> Daniel Halperin wrote:
>> > Hi,
>> >
>> > I have two identical Dell Inspiron 530n desktops running latest w-t
>> > (07e789c5094735747b3df8a7840f61467575ba9e, master 2011-05-04) on
>> > Ubuntu 10.04.2 LTS. I have uninstalled network-manager from both
>> > devices and, as far as I can tell, no software processes or daemons
>> > interfere with my wireless configurations.
>> >
>> > The AP machine has an AR9280-based device and an IWL5300 based device.
>> > I blacklist ath9k and iwlagn modules from loading on boot. It is
>> > running latest hostap.git, though I've seen the same issue with older
>> > versions.
>> >
>> > The client machine has one AR9380-based NIC, one IWL5300-based NIC,
>> > and one RT2800pci NIC. I blacklist ath9k, iwlagn, and rt2800pci from
>> > loading on boot.
>> >
>> > When I set up the client to connect (using iwconfig essid) to the AP
>> > (no encryption, channel 48 with HT40-) and run iperf, I sometimes see
>> > 2-second drops of the connection. I run iperf to generate elastic TCP
>> > flows that see ~150 Mbps, and in parallel I run ping <AP> -i 0.2.
>> > Here's the ping log:
>>
>> Your timing couldn't be better. :)
>> https://patchwork.kernel.org/patch/753862/
Thanks! I'll give it a whirl.
>
> Hm, is ath9k in AP mode ?
> That fix is meant primarily for station mode.
>
> Disabling ANI would be useful to narrow down the issue.
> (Since long calibration is every 30 seconds).
Yes, one side is AP and the other side is client.
What is ANI and how do I disable it? (Is there a website I should be
looking at? A quick search didn't pull anything up).
Thanks!
Dan
Sujith wrote:
> Daniel Halperin wrote:
> > Hi,
> >
> > I have two identical Dell Inspiron 530n desktops running latest w-t
> > (07e789c5094735747b3df8a7840f61467575ba9e, master 2011-05-04) on
> > Ubuntu 10.04.2 LTS. I have uninstalled network-manager from both
> > devices and, as far as I can tell, no software processes or daemons
> > interfere with my wireless configurations.
> >
> > The AP machine has an AR9280-based device and an IWL5300 based device.
> > I blacklist ath9k and iwlagn modules from loading on boot. It is
> > running latest hostap.git, though I've seen the same issue with older
> > versions.
> >
> > The client machine has one AR9380-based NIC, one IWL5300-based NIC,
> > and one RT2800pci NIC. I blacklist ath9k, iwlagn, and rt2800pci from
> > loading on boot.
> >
> > When I set up the client to connect (using iwconfig essid) to the AP
> > (no encryption, channel 48 with HT40-) and run iperf, I sometimes see
> > 2-second drops of the connection. I run iperf to generate elastic TCP
> > flows that see ~150 Mbps, and in parallel I run ping <AP> -i 0.2.
> > Here's the ping log:
>
> Your timing couldn't be better. :)
> https://patchwork.kernel.org/patch/753862/
Hm, is ath9k in AP mode ?
That fix is meant primarily for station mode.
Disabling ANI would be useful to narrow down the issue.
(Since long calibration is every 30 seconds).
Sujith
Daniel Halperin wrote:
> Hi,
>
> I have two identical Dell Inspiron 530n desktops running latest w-t
> (07e789c5094735747b3df8a7840f61467575ba9e, master 2011-05-04) on
> Ubuntu 10.04.2 LTS. I have uninstalled network-manager from both
> devices and, as far as I can tell, no software processes or daemons
> interfere with my wireless configurations.
>
> The AP machine has an AR9280-based device and an IWL5300 based device.
> I blacklist ath9k and iwlagn modules from loading on boot. It is
> running latest hostap.git, though I've seen the same issue with older
> versions.
>
> The client machine has one AR9380-based NIC, one IWL5300-based NIC,
> and one RT2800pci NIC. I blacklist ath9k, iwlagn, and rt2800pci from
> loading on boot.
>
> When I set up the client to connect (using iwconfig essid) to the AP
> (no encryption, channel 48 with HT40-) and run iperf, I sometimes see
> 2-second drops of the connection. I run iperf to generate elastic TCP
> flows that see ~150 Mbps, and in parallel I run ping <AP> -i 0.2.
> Here's the ping log:
Your timing couldn't be better. :)
https://patchwork.kernel.org/patch/753862/
Sujith
On Wed, May 4, 2011 at 4:42 PM, Daniel Halperin
<[email protected]> wrote:
> Hi,
>
> I have two identical Dell Inspiron 530n desktops running latest w-t
> (07e789c5094735747b3df8a7840f61467575ba9e, master 2011-05-04) on
> Ubuntu 10.04.2 LTS. I have uninstalled network-manager from both
> devices and, as far as I can tell, no software processes or daemons
> interfere with my wireless configurations.
>
> The AP machine has an AR9280-based device and an IWL5300 based device.
> I blacklist ath9k and iwlagn modules from loading on boot. It is
> running latest hostap.git, though I've seen the same issue with older
> versions.
>
> The client machine has one AR9380-based NIC, one IWL5300-based NIC,
> and one RT2800pci NIC. I blacklist ath9k, iwlagn, and rt2800pci from
> loading on boot.
>
> When I set up the client to connect (using iwconfig essid) to the AP
> (no encryption, channel 48 with HT40-) and run iperf, I sometimes see
> 2-second drops of the connection. I run iperf to generate elastic TCP
> flows that see ~150 Mbps, and in parallel I run ping <AP> -i 0.2.
> Here's the ping log:
>
> 64 bytes from 192.168.1.2: icmp_seq=622 ttl=64 time=107 ms
> 64 bytes from 192.168.1.2: icmp_seq=623 ttl=64 time=117 ms
> 64 bytes from 192.168.1.2: icmp_seq=624 ttl=64 time=125 ms
> 64 bytes from 192.168.1.2: icmp_seq=625 ttl=64 time=2152 ms
> 64 bytes from 192.168.1.2: icmp_seq=626 ttl=64 time=1989 ms
> 64 bytes from 192.168.1.2: icmp_seq=627 ttl=64 time=1779 ms
> 64 bytes from 192.168.1.2: icmp_seq=628 ttl=64 time=1570 ms
> 64 bytes from 192.168.1.2: icmp_seq=629 ttl=64 time=1360 ms
> 64 bytes from 192.168.1.2: icmp_seq=630 ttl=64 time=1150 ms
> 64 bytes from 192.168.1.2: icmp_seq=631 ttl=64 time=950 ms
> 64 bytes from 192.168.1.2: icmp_seq=632 ttl=64 time=750 ms
> 64 bytes from 192.168.1.2: icmp_seq=633 ttl=64 time=550 ms
> 64 bytes from 192.168.1.2: icmp_seq=634 ttl=64 time=340 ms
> 64 bytes from 192.168.1.2: icmp_seq=635 ttl=64 time=130 ms
> 64 bytes from 192.168.1.2: icmp_seq=636 ttl=64 time=2.73 ms
> 64 bytes from 192.168.1.2: icmp_seq=637 ttl=64 time=1.18 ms
> 64 bytes from 192.168.1.2: icmp_seq=638 ttl=64 time=1.18 ms
> 64 bytes from 192.168.1.2: icmp_seq=639 ttl=64 time=1.18 ms
> 64 bytes from 192.168.1.2: icmp_seq=640 ttl=64 time=1.18 ms
>
> you can see that ping times are large while the TCP flow is active,
> but drop to about 1.18ms after it stops. You can also clearly see the
> pings get backed-up for 2 seconds and then release. This tends to
> happen in the last 5 seconds of a 30s TCP flow, which starts almost
> immediately after association. I wonder if it might be related to some
> event that may get triggered 30s after association in either hostap or
> mac80211 or ath9k.
>
> This is reproducible (albeit infrequently) with the stock w-t kernel;
> I've also generated a version of the code in which I print out
> messages (KERN_INFO priority) inside of minstrel_ht whenever get_rate
> is called and whenever tx_status is called. I verified that there is
> **NO LOSS** measured by either side. Also, the gap in the messages is
> nearly exactly 2 seconds long, e.g., 2.03 seconds.
>
> Any thoughts as to what could be causing this?
>
> A final, but probably wrong, note. This seems to be (qualitatively)
> harder to reproduce if I don't compile in rt2800pci support. But, I
> blacklist the modules and I've verified that none of them are loaded
> on boot, so I don't know why this would be a problem.
I seem to have found a better way to make it reproducible: Once it
triggers once, if I run:
ifconfig wlan1 down
ifconfig wlan1 up 192.168.1.11
iwconfig wlan1 essid csitool
iperf -c 192.168.1.2 -i1
it will trigger again. Here's a representative iperf log:
iperf -c 192.168.1.2 -i1 -t 33
------------------------------------------------------------
Client connecting to 192.168.1.2, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 192.168.1.11 port 54479 connected with 192.168.1.2 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0- 1.0 sec 13.3 MBytes 111 Mbits/sec
[ 3] 1.0- 2.0 sec 18.0 MBytes 151 Mbits/sec
[ 3] 2.0- 3.0 sec 16.3 MBytes 137 Mbits/sec
[ 3] 3.0- 4.0 sec 15.0 MBytes 126 Mbits/sec
[ 3] 4.0- 5.0 sec 15.6 MBytes 131 Mbits/sec
[ 3] 5.0- 6.0 sec 14.9 MBytes 125 Mbits/sec
[ 3] 6.0- 7.0 sec 13.4 MBytes 112 Mbits/sec
[ 3] 7.0- 8.0 sec 15.7 MBytes 132 Mbits/sec
[ 3] 8.0- 9.0 sec 15.7 MBytes 131 Mbits/sec
[ 3] 9.0-10.0 sec 16.2 MBytes 136 Mbits/sec
[ 3] 10.0-11.0 sec 17.6 MBytes 148 Mbits/sec
[ 3] 11.0-12.0 sec 16.8 MBytes 141 Mbits/sec
[ 3] 12.0-13.0 sec 16.8 MBytes 141 Mbits/sec
[ 3] 13.0-14.0 sec 17.6 MBytes 148 Mbits/sec
[ 3] 14.0-15.0 sec 10.8 MBytes 90.7 Mbits/sec
[ 3] 15.0-16.0 sec 15.8 MBytes 133 Mbits/sec
[ 3] 16.0-17.0 sec 16.0 MBytes 134 Mbits/sec
[ 3] 17.0-18.0 sec 16.7 MBytes 140 Mbits/sec
[ 3] 18.0-19.0 sec 14.7 MBytes 123 Mbits/sec
[ 3] 19.0-20.0 sec 15.8 MBytes 133 Mbits/sec
[ 3] 20.0-21.0 sec 16.0 MBytes 134 Mbits/sec
[ 3] 21.0-22.0 sec 14.9 MBytes 125 Mbits/sec
[ 3] 22.0-23.0 sec 15.7 MBytes 132 Mbits/sec
[ 3] 23.0-24.0 sec 15.2 MBytes 127 Mbits/sec
[ 3] 24.0-25.0 sec 13.9 MBytes 117 Mbits/sec
[ 3] 25.0-26.0 sec 14.1 MBytes 118 Mbits/sec
[ 3] 26.0-27.0 sec 16.4 MBytes 137 Mbits/sec
[ 3] 27.0-28.0 sec 15.0 MBytes 126 Mbits/sec
[ 3] 28.0-29.0 sec 9.70 MBytes 81.4 Mbits/sec
[ 3] 29.0-30.0 sec 0.00 Bytes 0.00 bits/sec
[ 3] 30.0-31.0 sec 1.68 MBytes 14.1 Mbits/sec
[ 3] 31.0-32.0 sec 10.2 MBytes 85.7 Mbits/sec
[ 3] 32.0-33.0 sec 11.1 MBytes 93.5 Mbits/sec
[ 3] 0.0-33.0 sec 467 MBytes 118 Mbits/sec