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Date:      Tue, 22 Jul 2014 11:18:53 -0400
From:      John Jasen <jjasen@gmail.com>
To:        FreeBSD Net <freebsd-net@freebsd.org>
Subject:   fastforward/routing: a 3 million packet-per-second system?
Message-ID:  <53CE80DD.9090109@gmail.com>

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Feedback and/or tips and tricks more than welcome.

Outstanding questions:

Would increasing the number of processor cores help?

Would a system where both processor QPI ports connect to each other
mitigate QPI bottlenecks?

Are there further performance optimizations I am missing?

Server Description:

The system in question is a Dell Poweredge R820, 16GB of RAM, and two
Intel(R) Xeon(R) CPU E5-4610 0 @ 2.40GHz.

Onboard, in a 16x PCIe slot, I have one Chelsio T-580-CR two-port 40GbE
NIC, and in an 8x slot, another T-580-CR dual port.

I am running FreeBSD 10.0-STABLE.

BIOS tweaks:

Hyperthreading (or Logical Processors) is turned off.
Memory Node Interleaving is turned off, but did not appear to impact
performance.

/boot/loader.conf contents:
#for CARP+PF testing
carp_load="YES"
#load cxgbe drivers.
cxgbe_load="YES"
#maxthreads appears to not exceed CPU.
net.isr.maxthreads=12
#bindthreads may be indicated when using cpuset(1) on interrupts
net.isr.bindthreads=1
#random guess based on googling
net.isr.maxqlimit=60480
net.link.ifqmaxlen=90000
#discussions with cxgbe maintainer and list led me to trying this.
Allows more interrupts
#to be fixed to CPUs, which in some cases, improves interrupt balancing.
hw.cxgbe.ntxq10g=16
hw.cxgbe.nrxq10g=16

/etc/sysctl.conf contents:

#the following is also enabled by rc.conf gateway_enable.
net.inet.ip.fastforwarding=1
#recommendations from BSD router project
kern.random.sys.harvest.ethernet=0
kern.random.sys.harvest.point_to_point=0
kern.random.sys.harvest.interrupt=0
#probably should be removed, as cxgbe does not seem to affect/be
affected by irq storm settings
hw.intr_storm_threshold=25000000
#based on Calomel.Org performance suggestions. 4x40GbE, seemed
reasonable to use 100GbE settings
kern.ipc.maxsockbuf=1258291200
net.inet.tcp.recvbuf_max=1258291200
net.inet.tcp.sendbuf_max=1258291200
#attempting to play with ULE scheduler, making it serve packets versus
netstat
kern.sched.slice=1
kern.sched.interact=1

/etc/rc.conf contains:

hostname="fbge1"
#should remove, especially given below duplicate entry
ifconfig_igb0="DHCP"
sshd_enable="YES"
#ntpd_enable="YES"
# Set dumpdev to "AUTO" to enable crash dumps, "NO" to disable
dumpdev="AUTO"
# OpenBSD PF options to play with later. very bad for raw packet rates.
#pf_enable="YES"
#pflog_enable="YES"
# enable packet forwarding
# these enable forwarding and fastforwarding sysctls. inet6 does not
have fastforward
gateway_enable="YES"
ipv6_gateway_enable="YES"
# enable OpenBSD ftp-proxy
# should comment out until actively playing with PF
ftpproxy_enable="YES"
#left in place, commented out from prior testing
#ifconfig_mlxen1="inet 172.16.2.1 netmask 255.255.255.0 mtu 9000"
#ifconfig_mlxen0="inet 172.16.1.1 netmask 255.255.255.0 mtu 9000"
#ifconfig_mlxen3="inet 172.16.7.1 netmask 255.255.255.0 mtu 9000"
#ifconfig_mlxen2="inet 172.16.8.1 netmask 255.255.255.0 mtu 9000"
# -lro and -tso options added per mailing list suggestion from Bjoern A.
Zeeb (bzeeb-lists at lists.zabbadoz.net)
ifconfig_cxl0="inet 172.16.3.1 netmask 255.255.255.0 mtu 9000 -lro -tso up"
ifconfig_cxl1="inet 172.16.4.1 netmask 255.255.255.0 mtu 9000 -lro -tso up"
ifconfig_cxl2="inet 172.16.5.1 netmask 255.255.255.0 mtu 9000 -lro -tso up"
ifconfig_cxl3="inet 172.16.6.1 netmask 255.255.255.0 mtu 9000 -lro -tso up"
# aliases instead of reconfiguring test clients. See above commented out
entries
ifconfig_cxl0_alias0="172.16.7.1 netmask 255.255.255.0"
ifconfig_cxl1_alias0="172.16.8.1 netmask 255.255.255.0"
ifconfig_cxl2_alias0="172.16.1.1 netmask 255.255.255.0"
ifconfig_cxl3_alias0="172.16.2.1 netmask 255.255.255.0"
# for remote monitoring/admin of the test device
ifconfig_igb0="inet 172.30.60.60 netmask 255.255.0.0"

Additional configurations:
cpuset-chelsio-6cpu-high
# Original provided by  Navdeep Parhar <nparhar@gmail.com>
# takes vmstat -ai output into a list, and assigns interrupts in order to
# the available CPU cores.
# Modified: to assign only to the 'high CPUs', ie: on core1.
# See: http://lists.freebsd.org/pipermail/freebsd-net/2014-July/039317.html
#!/usr/local/bin/bash
ncpu=12
irqlist=$(vmstat -ia | egrep 't4nex|t5nex|cxgbc' | cut -f1 -d: | cut -c4-)
i=6
for irq in $irqlist; do
        cpuset -l $i -x $irq
        i=$((i+1))
        [ $i -ge $ncpu ] && i=6
done

Client Description:

Two Intel(R) Xeon(R) CPU E5-2670 v2 @ 2.50GHz processors
64 GB ram
Mellanox Technologies MT27500 Family [ConnectX-3]
Centos 6.4 with updates
iperf3 installed from yum repositories: iperf3-3.0.3-3.el6.x86_64

Test setup:

I've found about 3 streams between Centos clients is about the best way
to get the most out of them.
Above certain points, the -b flag does not change results.
-N is an artifact from using TCP
-l is needed, as -M doesn't work for UDP.

I usually use launch scripts similar to the following:

 for i in `seq 41 60`; do ssh loader$i "export TIME=120; export
STREAMS=1; export PORT=52$i; export PKT=64; export RATE=2000m;
/root/iperf-test-8port-udp" & done

The scripts execute the following on each host.

#!/bin/bash
PORT1=$PORT
PORT2=$(($PORT+1000))
PORT3=$(($PORT+2000))
iperf3 -c loader41-40gbe -u -b 10000m -i 0  -N -l $PKT -t$TIME
-P$STREAMS -p$PORT1 &
iperf3 -c loader42-40gbe -u -b 10000m -i 0  -N -l $PKT -t$TIME
-P$STREAMS -p$PORT1 &
iperf3 -c loader43-40gbe -u -b 10000m -i 0  -N -l $PKT -t$TIME
-P$STREAMS -p$PORT1 &
... (through all clients and all three ports) ...
iperf3 -c loader60-40gbe -u -b 10000m -i 0  -N -l $PKT -t$TIME
-P$STREAMS -p$PORT3 &


Results:

Summarized, netstat -w 1 -q 240 -bd, run through:
cat test4-tuning | egrep -v {'packets | input '} | awk '{ipackets+=$1}
{idrops+=$3} {opackets+=$5} {odrops+=$9} END {print "input "
ipackets/NR, "idrops " idrops/NR, "opackets " opackets/NR, "odrops "
odrops/NR}'

input 1.10662e+07 idrops 8.01783e+06 opackets 3.04516e+06 odrops 3152.4

Snapshot of raw output:

           input        (Total)           output
   packets  errs idrops      bytes    packets  errs      bytes colls drops
  11189148     0 7462453 1230805216    3725006     0  409750710     0   799
  10527505     0 6746901 1158024978    3779096     0  415700708     0   127
  10606163     0 6850760 1166676673    3751780     0  412695761     0  1535
  10749324     0 7132014 1182425799    3617558     0  397930956     0  5972
  10695667     0 7022717 1176521907    3669342     0  403627236     0  1461
  10441173     0 6762134 1148528662    3675048     0  404255540     0  6021
  10683773     0 7005635 1175215014    3676962     0  404465671     0  2606
  10869859     0 7208696 1195683372    3658432     0  402427698     0   979
  11948989     0 8310926 1314387881    3633773     0  399714986     0   725
  12426195     0 8864415 1366877194    3562311     0  391853156     0  2762
  13006059     0 9432389 1430661751    3570067     0  392706552     0  5158
  12822243     0 9098871 1410443600    3715177     0  408668500     0  4064
  13317864     0 9683602 1464961374    3632156     0  399536131     0  3684
  13701905     0 10182562 1507207982    3523101     0  387540859     0 
8690
  13820227     0 10244870 1520221820    3562038     0  391823322     0 
2426
  14437060     0 10955483 1588073033    3480105     0  382810557     0 
2619
  14518471     0 11119573 1597028105    3397439     0  373717355     0 
5691
  14890287     0 11675003 1637926521    3199812     0  351978304     0
11007
  14923610     0 11749091 1641594441    3171436     0  348857468     0 
7389
  14738704     0 11609730 1621254991    3117715     0  342948394     0 
2597
  14753975     0 11549735 1622935026    3207393     0  352812846     0 
4798








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