This bug has been copied from bug #593801 and has been proposed to be backported to 5.5 z-stream (EUS).
in 2.6.18-194.10.1.el5
An advisory has been issued which should help the problem described in this bug report. This report is therefore being closed with a resolution of ERRATA. For more information on therefore solution and/or where to find the updated files, please follow the link below. You may reopen this bug report if the solution does not work for you. http://rhn.redhat.com/errata/RHSA-2010-0610.html
Technical note added. If any revisions are required, please edit the "Technical Notes" field accordingly. All revisions will be proofread by the Engineering Content Services team. New Contents: When TPA (Transparent Packet Aggregation) was used with a bnx2x network driver (10 Gb), TCP bandwidth problems occurred, causing transfer rate slowdowns (down to 400 Kb) and network delays. The network traces shown that the reason for the TCP bandwidth problems were TCP delayed ACK mechanisms. This update improves the packet-handling code so that network ACKs are not delayed when using TPA, GRO (Generic Receive Offload), or LRO (Large Receive Offload) with the bnx2x driver, thus leading to increased networking performance.