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Date:      Mon, 7 Dec 2009 14:41:55 +0200
From:      "Noisex" <noisex@apollo.lv>
To:        <freebsd-performance@freebsd.org>
Subject:   FreeBSD TCP tuning and performance
Message-ID:  <056c01ca773a$a88f69e0$f9ae3da0$@lv>
In-Reply-To: <b8592ed80911300352n6e05be32l1435bb1b27ece071@mail.gmail.com>
References:  <4B108A18.207@truschinski.de>	<B36EDB3F-79AB-4365-9E22-AA7A9E838393@gmail.com>	<584ec6bb0911291330o11fba282y400e0abf121f5e7f@mail.gmail.com> <b8592ed80911300352n6e05be32l1435bb1b27ece071@mail.gmail.com>

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Hi! I have a problem with TCP performance on FBSD boxes with 1Gbps net =
i-faces (Broadcom NetXtreme II BCM5708 1000Base-T (B2)). Currently i use =
FBSD 7.1 AMD64.

The test lab: 2 x (server-client) HP Proliant G5 DL360 (quad-core/8gb =
ram, raid 5 SAS).

For net benchmark i used nuttcp and iperf.

The servers (client-server) are in 1 VLAN.

The results on 1Gbps (down & up):

   63.4375 MB /   1.00 sec =3D  532.1332 Mbps
   64.3750 MB /   1.00 sec =3D  540.0426 Mbps
   62.8125 MB /   1.00 sec =3D  526.8963 Mbps
   64.5625 MB /   1.00 sec =3D  541.6318 Mbps
   63.9375 MB /   1.00 sec =3D  536.3595 Mbps
   63.7500 MB /   1.00 sec =3D  534.7566 Mbps
   63.0000 MB /   1.00 sec =3D  528.5003 Mbps
   63.5000 MB /   1.00 sec =3D  532.7150 Mbps
   64.0000 MB /   1.00 sec =3D  536.8586 Mbps
   63.5625 MB /   1.00 sec =3D  533.2452 Mbps
  =20
   637.6688 MB /  10.02 sec =3D  533.9108 Mbps 9 %TX 9 %RX 9 =
host-retrans 0.67 msRTT

   25.5625 MB /   1.00 sec =3D  214.3916 Mbps
   30.8750 MB /   1.00 sec =3D  259.0001 Mbps
   29.9375 MB /   1.00 sec =3D  251.1347 Mbps
   27.1875 MB /   1.00 sec =3D  228.0669 Mbps
   30.5000 MB /   1.00 sec =3D  255.8533 Mbps
   30.2500 MB /   1.00 sec =3D  253.7551 Mbps
   26.8125 MB /   1.00 sec =3D  224.9211 Mbps
   30.3750 MB /   1.00 sec =3D  254.8047 Mbps
   30.3750 MB /   1.00 sec =3D  254.8050 Mbps
   30.0625 MB /   1.00 sec =3D  252.1835 Mbps

  292.2155 MB /  10.02 sec =3D  244.6825 Mbps 10 %TX 12 %RX 0 =
host-retrans 0.71 msRTT

As you can see down is littlebit more than half of full link speed. And =
upload is only 20-25% of full link.

I tried to change a lot sysctl params but without a big results. =
Currenlty my entries in /etc/sysctl.conf which regarding to TCP:

#kernel tuning, tcp
kern.ipc.somaxconn=3D2048
kern.ipc.nmbclusters=3D32768

kern.ipc.maxsockbuf=3D8388608
net.inet.tcp.sendbuf_max=3D16777216
net.inet.tcp.recvbuf_max=3D16777216
net.inet.tcp.inflight.enable=3D0
net.inet.tcp.sendspace=3D65536
net.inet.tcp.recvspace=3D65536
net.inet.udp.recvspace=3D65536
net.inet.tcp.inflight.enable=3D0
net.inet.tcp.rfc1323=3D1
net.inet.tcp.sack.enable=3D1
net.inet.tcp.path_mtu_discovery=3D1
net.inet.tcp.sendbuf_auto=3D1
net.inet.tcp.sendbuf_inc=3D16384
net.inet.tcp.recvbuf_auto=3D1
net.inet.tcp.recvbuf_inc=3D524288

Do you have some kind suggestion what i could to change to increase the =
performance of TCP?=20

Besides when i make the benchamrks i run the sniffer to see whats =
happening with network..sometimes i saw that window size is 0...does it =
mean that server can't handle something or recieve buffer size is to =
small?

p.s sory for my bad english :)
Noisex





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