On Tue, 07 Mar 2006 13:44:51 -0800
Matt Leininger [off-list ref] wrote:

On Mon, 2006-03-06 at 19:13 -0800, Shirley Ma wrote:

quoted

quoted

More likely you are getting hit by the fact that TSO prevents the

congestion
window from increasing properly. This was fixed in 2.6.15 (around mid
of Nov 2005). 

Yep, I noticed the same problem. After updating to the new kernel, the
performance are much better, but it's still lower than before.

 Here is an updated version of OpenIB IPoIB performance for various
kernels with and without one of the TSO patches.  The netperf
performance for the latest kernels has not improved the TSO performance
drop.

  Any comments or suggestions would be appreciated.

  - Matt

Configuration information? like did you increase the tcp_rmem, tcp_wmem?
Tcpdump traces of what is being sent and available window?
Is IB using NAPI or just doing netif_rx()?