RFC: issues concerning the next NAPI interface

[Shirley Ma]

> Just to be clear, in the previous email I posted on this thread, I
> described a worst-case network ping-pong test case (send a packet, wait
> for reply), and found out that a deffered interrupt scheme just damaged
> the performance of the test case. 

When splitting rx and tx handler, I found some performance gain by 
deffering interrupt scheme in tx not rx in IPoIB driver.

Shirley