- Download iperf-2.0.4.tar.gz into a directory and place the patch file 
(attached) in the same directory.
- Unpack the source tarball:
gtar xvfz iperf-2.0.4.tar.gz
- Uncompress the patch file:
gunzip iperf-2.0.4-pthreads-rt.patch
- Enter the uncompressed source dir
cd iperf-2.0.4
- Run the configure script making sure to specify GNU make be used rather than 
Solaris make:
MAKE=gmake ./configure
- Apple the patch to the configured source directories using GNU patch util 
rather than Solaris patch:
gpatch -p1 < ../iperf-2.0.4-pthreads-rt.patch
- Build the source with GNU make rather than Solaris make:
gmake all

Hopefully if all goes well, the compiled iperf util will be in the ./src 
directory.