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Date: Sun, 29 Nov 2015 03:41:20 +0100
From: Niklas Cassel <niklas.cassel@...s.com>
To: Eric Dumazet <eric.dumazet@...il.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: network stream fairness
Greetings fellow hackers :)
I have managed to reproduce my streaming unfairness with the intel e1000 driver.
I believe that commit
605ad7f184b6 ("tcp: refine TSO autosizing")
changed the behavior for 100 Mbps NIC:s with TSO enabled.
I have 2 e1000 cards connected in the same computer, with a network cable
connecting the NIC:s directly.
Please note that I used a intel e1000 card/driver,
since the e1000e driver turns off TSO when setting the speed to 100.
I also added netif_set_gso_max_size(netdev, 16384) to the e1000 driver,
but that did not affect the end result.
See iperf results with and without 605ad7f184b6 at the end of this mail.
When talking to Eric I've learned that TCP is not fair by design,
so I guess that one could argue that we previously, by coincidence,
happened to be more fair, and that we now just happen to be not as fair.
If I didn't know that though, my expectations would be that the
Fair Queue packet scheduler would behave just like its name says, fair. :P
Working within normal parameters or not, at least now we know that the patch
actually did cause a change in behavior for 100 Mbps NIC:s with TSO enabled.
My setup script, to not use loopback, etc., looks like this (thx Steve Kehlet):
tc qdisc replace dev eth0 root fq
tc qdisc replace dev eth2 root fq
ethtool -s eth2 speed 100 duplex full autoneg on
ethtool -s eth0 speed 100 duplex full autoneg on
ip addr add 10.50.0.1/24 dev eth2
ip addr add 10.50.1.1/24 dev eth0
iptables -t nat -A POSTROUTING -s 10.50.0.1 -d 10.60.1.1 -j SNAT --to-source 10.60.0.1
iptables -t nat -A PREROUTING -d 10.60.0.1 -j DNAT --to-destination 10.50.0.1
iptables -t nat -A POSTROUTING -s 10.50.1.1 -d 10.60.0.1 -j SNAT --to-source 10.60.1.1
iptables -t nat -A PREROUTING -d 10.60.1.1 -j DNAT --to-destination 10.50.1.1
ip route add 10.60.1.1 dev eth2
arp -i eth2 -s 10.60.1.1 00:11:22:33:44:55 # MAC address of eth0
ip route add 10.60.0.1 dev eth0
arp -i eth0 -s 10.60.0.1 55:44:33:22:11:00 # MAC address of eth2
Running iperf locked to a certain NIC:
iperf3 -B 10.50.0.1 -s
iperf3 -B 10.50.1.1 -c 10.60.0.1 -t 240 -P 2
Vanilla 4.3, sch_fq, e1000 driver, 100 Mbps speed, TSO on:
Connecting to host 10.60.0.1, port 5201
[ 4] local 10.50.1.1 port 40698 connected to 10.60.0.1 port 5201
[ 6] local 10.50.1.1 port 39755 connected to 10.60.0.1 port 5201
[ ID] Interval Transfer Bandwidth Retr Cwnd
[ 4] 0.00-1.00 sec 5.78 MBytes 48.4 Mbits/sec 0 46.7 KBytes
[ 6] 0.00-1.00 sec 5.70 MBytes 47.8 Mbits/sec 0 48.1 KBytes
[SUM] 0.00-1.00 sec 11.5 MBytes 96.2 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 1.00-2.00 sec 5.53 MBytes 46.4 Mbits/sec 0 49.5 KBytes
[ 6] 1.00-2.00 sec 5.65 MBytes 47.4 Mbits/sec 0 48.1 KBytes
[SUM] 1.00-2.00 sec 11.2 MBytes 93.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 2.00-3.00 sec 5.65 MBytes 47.4 Mbits/sec 0 49.5 KBytes
[ 6] 2.00-3.00 sec 5.59 MBytes 46.9 Mbits/sec 0 48.1 KBytes
[SUM] 2.00-3.00 sec 11.2 MBytes 94.3 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 3.00-4.00 sec 4.86 MBytes 40.8 Mbits/sec 0 49.5 KBytes
[ 6] 3.00-4.00 sec 6.44 MBytes 54.0 Mbits/sec 0 66.5 KBytes
[SUM] 3.00-4.00 sec 11.3 MBytes 94.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 4.00-5.00 sec 4.01 MBytes 33.6 Mbits/sec 0 49.5 KBytes
[ 6] 4.00-5.00 sec 7.22 MBytes 60.5 Mbits/sec 0 66.5 KBytes
[SUM] 4.00-5.00 sec 11.2 MBytes 94.2 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 5.00-6.00 sec 4.31 MBytes 36.2 Mbits/sec 0 49.5 KBytes
[ 6] 5.00-6.00 sec 6.84 MBytes 57.3 Mbits/sec 0 66.5 KBytes
[SUM] 5.00-6.00 sec 11.1 MBytes 93.5 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 6.00-7.00 sec 4.44 MBytes 37.2 Mbits/sec 0 49.5 KBytes
[ 6] 6.00-7.00 sec 6.91 MBytes 58.0 Mbits/sec 0 66.5 KBytes
[SUM] 6.00-7.00 sec 11.3 MBytes 95.2 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 7.00-8.00 sec 4.31 MBytes 36.2 Mbits/sec 0 49.5 KBytes
[ 6] 7.00-8.00 sec 6.84 MBytes 57.3 Mbits/sec 0 66.5 KBytes
[SUM] 7.00-8.00 sec 11.1 MBytes 93.5 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 8.00-9.00 sec 4.50 MBytes 37.7 Mbits/sec 0 49.5 KBytes
[ 6] 8.00-9.00 sec 6.76 MBytes 56.7 Mbits/sec 0 66.5 KBytes
[SUM] 8.00-9.00 sec 11.3 MBytes 94.4 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 9.00-10.00 sec 4.19 MBytes 35.2 Mbits/sec 0 49.5 KBytes
[ 6] 9.00-10.00 sec 6.99 MBytes 58.6 Mbits/sec 0 66.5 KBytes
[SUM] 9.00-10.00 sec 11.2 MBytes 93.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 10.00-11.00 sec 4.25 MBytes 35.7 Mbits/sec 0 49.5 KBytes
[ 6] 10.00-11.00 sec 6.99 MBytes 58.6 Mbits/sec 0 66.5 KBytes
[SUM] 10.00-11.00 sec 11.2 MBytes 94.3 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 11.00-12.00 sec 4.19 MBytes 35.2 Mbits/sec 0 49.5 KBytes
[ 6] 11.00-12.00 sec 7.06 MBytes 59.3 Mbits/sec 0 66.5 KBytes
[SUM] 11.00-12.00 sec 11.3 MBytes 94.4 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 12.00-13.00 sec 4.50 MBytes 37.7 Mbits/sec 0 49.5 KBytes
[ 6] 12.00-13.00 sec 6.68 MBytes 56.1 Mbits/sec 0 66.5 KBytes
[SUM] 12.00-13.00 sec 11.2 MBytes 93.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 13.00-14.00 sec 4.01 MBytes 33.6 Mbits/sec 0 49.5 KBytes
[ 6] 13.00-14.00 sec 7.22 MBytes 60.5 Mbits/sec 0 66.5 KBytes
[SUM] 13.00-14.00 sec 11.2 MBytes 94.2 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-14.00 sec 64.5 MBytes 38.7 Mbits/sec 0 sender
[ 4] 0.00-14.00 sec 64.5 MBytes 38.6 Mbits/sec receiver
[ 6] 0.00-14.00 sec 92.9 MBytes 55.6 Mbits/sec 0 sender
[ 6] 0.00-14.00 sec 92.7 MBytes 55.6 Mbits/sec receiver
[SUM] 0.00-14.00 sec 157 MBytes 94.3 Mbits/sec 0 sender
[SUM] 0.00-14.00 sec 157 MBytes 94.2 Mbits/sec receiver
iperf Done.
Kernel 4.3, 605ad7f184b6 reverted, sch_fq, e1000 driver, 100 Mbps speed, TSO on:
Connecting to host 10.60.0.1, port 5201
[ 4] local 10.50.1.1 port 40949 connected to 10.60.0.1 port 5201
[ 6] local 10.50.1.1 port 39238 connected to 10.60.0.1 port 5201
[ ID] Interval Transfer Bandwidth Retr Cwnd
[ 4] 0.00-1.00 sec 6.09 MBytes 51.1 Mbits/sec 0 219 KBytes
[ 6] 0.00-1.00 sec 6.05 MBytes 50.8 Mbits/sec 0 219 KBytes
[SUM] 0.00-1.00 sec 12.1 MBytes 102 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 1.00-2.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[ 6] 1.00-2.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[SUM] 1.00-2.00 sec 11.3 MBytes 94.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 2.00-3.00 sec 5.47 MBytes 45.9 Mbits/sec 0 219 KBytes
[ 6] 2.00-3.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[SUM] 2.00-3.00 sec 11.1 MBytes 93.3 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 3.00-4.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[ 6] 3.00-4.00 sec 5.47 MBytes 45.9 Mbits/sec 0 219 KBytes
[SUM] 3.00-4.00 sec 11.1 MBytes 93.3 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 4.00-5.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[ 6] 4.00-5.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[SUM] 4.00-5.00 sec 11.3 MBytes 94.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 5.00-6.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[ 6] 5.00-6.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[SUM] 5.00-6.00 sec 11.3 MBytes 94.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 6.00-7.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[ 6] 6.00-7.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[SUM] 6.00-7.00 sec 11.3 MBytes 94.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 7.00-8.00 sec 5.47 MBytes 45.9 Mbits/sec 0 219 KBytes
[ 6] 7.00-8.00 sec 5.47 MBytes 45.9 Mbits/sec 0 219 KBytes
[SUM] 7.00-8.00 sec 10.9 MBytes 91.7 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 8.00-9.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[ 6] 8.00-9.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[SUM] 8.00-9.00 sec 11.3 MBytes 94.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 9.00-10.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[ 6] 9.00-10.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[SUM] 9.00-10.00 sec 11.3 MBytes 94.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 10.00-11.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[ 6] 10.00-11.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[SUM] 10.00-11.00 sec 11.3 MBytes 94.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 11.00-12.00 sec 5.47 MBytes 45.9 Mbits/sec 0 219 KBytes
[ 6] 11.00-12.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[SUM] 11.00-12.00 sec 11.1 MBytes 93.3 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 12.00-13.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[ 6] 12.00-13.00 sec 5.47 MBytes 45.9 Mbits/sec 0 219 KBytes
[SUM] 12.00-13.00 sec 11.1 MBytes 93.3 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ 4] 13.00-14.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[ 6] 13.00-14.00 sec 5.65 MBytes 47.4 Mbits/sec 0 219 KBytes
[SUM] 13.00-14.00 sec 11.3 MBytes 94.8 Mbits/sec 0
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-14.00 sec 79.0 MBytes 47.3 Mbits/sec 0 sender
[ 4] 0.00-14.00 sec 78.6 MBytes 47.1 Mbits/sec receiver
[ 6] 0.00-14.00 sec 79.0 MBytes 47.3 Mbits/sec 0 sender
[ 6] 0.00-14.00 sec 78.6 MBytes 47.1 Mbits/sec receiver
[SUM] 0.00-14.00 sec 158 MBytes 94.7 Mbits/sec 0 sender
[SUM] 0.00-14.00 sec 157 MBytes 94.2 Mbits/sec receiver
iperf Done.
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