Always Do The Math!

I just spent the last three weeks futzing with proof of concept code, trying to get a client/server setup to support the performance requirements of the client. I was researching all kinds of tcp kernel parameters, reading up on the network stack, java.nio.Selectors, asynchronous I/O, TCP receive windows, doing everything I could to get the numbers to what the client was asking for. Finally, after I had gotten the number to about 4x less than what the client wanted, I did a simple math calculation to see how close to the theoretical bandwidth of GigE I was getting. Turns out I was already using about .8Gbps!! Did the math on the performance that the client wants, it would require 4Gbps ethernet!! Could have saved myself and the client three weeks of time if I had simply done that calculation (correctly) up front!!!