[Codel] FQ_Codel lwn draft article review

Rick Jones rick.jones2 at hp.com
Mon Nov 26 16:13:54 EST 2012

On 11/24/2012 08:19 AM, Dave Taht wrote:
> On Sat, Nov 24, 2012 at 1:07 AM, Toke Høiland-Jørgensen <toke at toke.dk> wrote:
>> "Paul E. McKenney" <paulmck at linux.vnet.ibm.com> writes:
>> The UDP ping tests tend to not work so well on a loaded link,
>> however, since netperf stops sending packets after detecting
>> (excessive(?)) loss. Which is why you see only see the UDP ping times on
>> the first part of the graph.
> Netperf stops UDP_STREAM exchanges after the first lost udp packet.

The UDP_STREAM test will keep blasting along until the end-of-test timer 
fires.  It is the non-burst-mode UDP_RR test which comes to a halt on 
the first lost datagram.

> After staring at the tons of data collected over the past year, on
> wifi, I'm willing to strongly suggest we just drop TCP packets after
> 500ms in the wifi stack, period, as that exceeds the round trip
> timeout...

How does WiFi "know" what the TCP RTO for a given flow happens to be? 
There is no 500 millisecond ceiling on the TCP RTO.

rick jones

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