DAST: Iperf - Large differences in measured throughput ttcp compared to iperf - Knut.Hellebo --at-- nho.hydro.com
>Date: Wed, 8 Mar 2006 08:03:25 -0600
>To: Knut.Hellebo --at-- nho.hydro.com
>Subject: DAST: Iperf - Large differences in measured throughput ttcp
compared to iperf - Knut.Hellebo --at-- nho.hydro.com
>
>
>Contacting DAST re: Request for information about Iperf
>From: Knut Hellebø <Knut.Hellebo --at-- nho.hydro.com>
>
>Subject: Large differences in measured throughput ttcp compared to iperf
>
>Question/Comment:
>Regards,
>
>I have used iperf and ttcp and the throughput numbers obtained differ
wastly. How can this be ? Here are some examples (server is a GigE linux
box, client is a GigE IRIX box)
>
>[root --at-- server root]# ttcp -rs -b 524288 -fm
>ttcp-r: buflen=8192, nbuf=2048, align=16384/0, port=5001,
sockbufsize=524288 tcp
>ttcp-r: socket
>ttcp-r: rcvbuf
>ttcp-r: accept from 136.164.208.7
>ttcp-r: 16777216 bytes in 0.15 real seconds = 855.93 Mbit/sec +++
>ttcp-r: 2830 I/O calls, msec/call = 0.05, calls/sec = 18924.07
>ttcp-r: 0.0user 0.0sys 0:00real 28% 0i+0d 0maxrss 1+0pf 0+0csw
>You have new mail in /var/spool/mail/root
>[root --at-- server root]# /local/bin/iperf -s -w 512k -fm
>------------------------------------------------------------
>Server listening on TCP port 5001
>TCP window size: 1.00 MByte (WARNING: requested 0.50 MByte)
>------------------------------------------------------------
>[ 4] local 136.164.208.4 port 5001 connected with 136.164.208.7 port 13878
>[ 4] 0.0-10.9 sec 171 MBytes 132 Mbits/sec
>
>user --at-- client /h/user> ttcp -ts -fm -b 524288 server
>ttcp-t: buflen=8192, nbuf=2048, align=16384/0, port=5001,
sockbufsize=524288 tcp -> server
>ttcp-t: socket
>ttcp-t: sndbuf
>ttcp-t: connect
>ttcp-t: 16777216 bytes in 0.15 real seconds = 870.06 Mbit/sec +++
>ttcp-t: 2048 I/O calls, msec/call = 0.07, calls/sec = 13920.89
>ttcp-t: 0.0user 0.0sys 0:00real 21% 832maxrss 0+0pf 1329+1csw
>user --at-- client /h/user> iperf -w 512k -fm -c client
>------------------------------------------------------------
>Client connecting to server, TCP port 5001
>TCP window size: 0.50 MByte (WARNING: requested 0.50 MByte)
>------------------------------------------------------------
>[ 3] local 136.164.208.7 port 13878 connected with 136.164.208.4 port 5001
>[ 3] 0.0-10.9 sec 171 MBytes 132 Mbits/sec
>
>
>
--
Mitch Kutzko | mitch --at-- dast.nlanr.net | mitch --at-- ncsa.uiuc.edu | 217-333-1199
http://hobbes.ncsa.uiuc.edu/