netdev - Re: Linux TCP's Robustness to Multipath Packet Reordering

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Date:	Tue, 26 Apr 2011 20:00:11 +0200
From:	Dominik Kaspar <dokaspar.ietf@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Carsten Wolff <carsten@...ffcarsten.de>, netdev@...r.kernel.org
Subject: Re: Linux TCP's Robustness to Multipath Packet Reordering

Hi Eric,

Here are the tcpdump files for the first TSO-disabled experiment, in a
full version and a short version with only the first 10000 packets:

http://home.simula.no/~kaspar/static/mptcp-emu-wlan-hspa-01-tos0-exp1-full.pcap
http://home.simula.no/~kaspar/static/mptcp-emu-wlan-hspa-01-tos0-exp1-short.pcap

By the way, the packets are sent from the server (x.x.x.189) to the
client interfaces (x.x.x.74) and (x.x.x.216) with the following
pattern (which is a non-bursty 128-bit approximation of scheduling
with a 600:400 ratio over primary path 0 and secondary path 1):

0010010100101001010010100101001010010100101001010010100101001010
0101001010010100101001010010100101001010010100101001010010100101

Greetings,
Dominik

On Tue, Apr 26, 2011 at 7:10 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> Le mardi 26 avril 2011 à 18:58 +0200, Dominik Kaspar a écrit :
>> Hi Eric,
>>
>> On Mon, Apr 25, 2011 at 5:38 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
>> >
>> > Since you have at sender a rule to spoof destination address of packets,
>> > you should make sure you dont send "super packets (up to 64Kbytes)",
>> > because it would stress the multipath more than you wanted to. This way,
>> > you send only normal packets (1500 MTU).
>> >
>> > ethtool -K eth0 tso off
>> > ethtool -K eth0 gso off
>> >
>> > I am pretty sure it should help your (atypic) workload.
>>
>> I made new experiments with the exact same multipath setup as before,
>> but disabled TSO and GSO on all involved Ethernet interfaces. However,
>> this did not seem to change much about TCP's behavior when packets are
>> striped over heterogeneous paths. You can see the results of four
>> 20-minute experiments on this plot:
>>
>> http://home.simula.no/~kaspar/static/mptcp-emu-wlan-hspa-01-tos0.png
>>
>> Cheers,
>> Dominik
>
> Hi Dominik
>
> Any chance to have a pcap file from sender side, of say first 10.000
> packets ?
>
>
>
>
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