Using HAproxy in web server benchmark configuration (e.g. SPECweb)?

[Hsin, Chih-fan]

Hi, have any one use HAproxy to run some web server benchmark testing?
I tried to see if I can use HAproxy in SPECweb2005 configuration, but I 
couldn't find a way. I want to use a set of web servers to serve as the System 
Under Test (SUT). The requests from clients to SUT can be distributed through 
HAproxy. However, the traffics from Primary Client and the Backend Simulator to 
SUT cannot be routed to the correct web server. At least, I didn't find a way 
yet.
Does any one have any similar experience?
Thanks,
Chih-fan Hsin