Comment 2 for bug 156748

This is a pretty serious performance issue. I've attached a patch against the original debian package to incorporate the Ingo Molnar fix (see Antonio above). It has great effect on system usage during iperf runs

bschmidt@lxbsc01:~/tmp$ time iperf -V -c ping.lrz-muenchen.de
------------------------------------------------------------
Client connecting to ping.lrz-muenchen.de, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 2001:4ca0:0:f000:211:43ff:fe7e:3a76 port 39596 connected with 2001:4ca0:0:101:250:56ff:fea9:56a1 port 5001
[ 3] 0.0-10.0 sec 1.03 GBytes 886 Mbits/sec

real 0m10.007s
user 0m2.244s
sys 0m13.769s

[System is very unresponsive during the test and iperf uses up to 180% cpu according to top]

bschmidt@lxbsc01:~/tmp$ sudo dpkg -i iperf_2.0.2-3.1_i386.deb
(Lese Datenbank ... 102562 Dateien und Verzeichnisse sind derzeit installiert.)
Vorbereiten zum Ersetzen von iperf 2.0.2-3 (durch iperf_2.0.2-3.1_i386.deb) ...
Entpacke Ersatz für iperf ...
Richte iperf ein (2.0.2-3.1) ...

bschmidt@lxbsc01:~/tmp$ time iperf -V -c ping.lrz-muenchen.de
------------------------------------------------------------
Client connecting to ping.lrz-muenchen.de, TCP port 5001
TCP window size: 16.0 KByte (default)
------------------------------------------------------------
[ 3] local 2001:4ca0:0:f000:211:43ff:fe7e:3a76 port 46070 connected with 2001:4ca0:0:101:250:56ff:fea9:56a1 port 5001
[ 3] 0.0-10.0 sec 1.06 GBytes 914 Mbits/sec

real 0m10.040s
user 0m0.120s
sys 0m4.748s

System is responsive, about 30% CPU usage

All of that on Ubuntu hardy. It would be highly appreciated if the Debian bug could be monitored and the bugfix be backported or integrated by Ubuntu before the hardy release.