tcp help

Hi,

I have to do some tests on tcp slow start for my final thesis. I
modified tcp_init_cwnd in tcp_input.c and tcp_select_initial_window in
tcp.h. Here I set cwnd to the value I want to test. So I have changed
both to the same value, did this on both my server and my client.

Was this enough? Are there any other values I havt to change?

I controlled the result with tcpdump. But most time it started with 3
packets, sometimes with 6 packets. Even if the initial window is
bigger for example 12. May it be that the first acknowledge is too
fast to send more packages?

I use Red Hat Linux 7.2 and a switched 100 MBit network. If I ping the
other host I get an RTT of 165 usec.

Thanks for your help.
Stephan