I've been experiencing problems with multiple TCP connections when initially trying to create >3 connections, it seems like the ARP request->reply makes some of the connections do a retry with the default RTO value (3000 ms).
This only occurs with the first connection attempt. Once the mac address is in the ARP tables, no delay is noticeable.

I am trying to lower this TO value, and found that it's primary initialized as 3000 ms
(2.6.32; ./include/net/tcp.h: 130) but could not find if it is affected by any kernel tunable.

It seems like some tunable values should affect TO value (tcp_frto / tcp_frto_response), but they don't ease my problem.

Can you advise if there's any way to decrease the amount of time spend before re-trying to send SYN, in case MAC record was not found in ARP table ?

Thanks a lot,