kern/163237: AR5416 as HostAP. Delays among clients when

Gustau Pérez gperez at entel.upc.edu
Wed Dec 14 20:20:10 UTC 2011


The following reply was made to PR kern/163237; it has been noted by GNATS.

From: =?ISO-8859-1?Q?Gustau_P=E9rez?= <gperez at entel.upc.edu>
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: kern/163237: AR5416 as HostAP. Delays among clients when
Date: Wed, 14 Dec 2011 19:55:33 +0100

 Further tests show that when an iPhone associates with the AP, the 
 problem appears. As soon as the iPhone deassociates the latency goes down.
 
 Some tests where made. The tree elements during the tests were: the AP 
 Box, an iPhone and a FreeBSD 10/CURRENT laptop. The laptop was sending 
 icmp messages to the AP while the iPhone was associated.
 
 The AP Box has the 192.168.1.100/24 address. The
 
 A first test consisted of sending 10 icmp messages per second from the 
 laptop to the AP Box. The command used was:
 
      ping -c 0.1 192.168.1.100
 
   When doing this test the latency was constantly growing untill the 
 time taken to reach the box and back got up to around 110ms, then it 
 fell to around 10ms (which quite big, I would say three orders of 
 magnitude.I would have expected about 0.5ms). The frequency of the 
 phenomenon was of around 80 icmp messages (that is about 8 seconds of 
 icmp messages).
 
    A second test consisted of sending 100 icmp messages per second to 
 the box. Now the behavior was different. The latency keep falling to 
 around 20ms and then it suddenly grew to around 110ms. The frequency 
 this time was of about 8 icmp messages.
 
     I can obtain traces and upload them somewhere and share the links.


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