Performance and Recommended Use of AD385A 10 Gigabit Ethernet SR Cards

Table Of Contents

Recommended Use Based on Performance and Design

HP recommends the following usage model to achieve the best performance:

• Run the AD385A cards in the highest performing PCI-X slots. Slots 3, 4, 5, and 6 on

each of the I/O bays are the recommended high performance PCI-X slots in the HP

Integrity rx8640 used in our performance testing. Please refer to the appropriate

Server Installation Guide for information on how to identify high performance slots.

• Configure Jumbo Frames (9000 MTU) if possible. Jumbo Frames can provide excellent

throughput with reduced CPU overhead. However, Jumbo Frames may not be usable in

all topologies. Please refer to the HP document “Boosting server-to-server Gigabit

Throughput with Jumbo Frames” for more information on advantages and recommended

usage models.

• The10 Gigabit driver is optimized for multiprocessor support. Best performance will be

achieved when running multiple data streams (TCP connections, for example) on a

system with four or more processors configured. The software will automatically assign

appropriate processor resources to each data stream. This is the default configuration in

HP-UX 11i v3.

• The10 Gigabit driver also supports the ability to look at received packets, identify those

belonging to the same TCP connection, perform reassembly and send the reassembled

segments to the upper layers. This helps to reduce CPU utilization. This feature is called

TCP packet reassembly in the driver. The performance gain that will be seen with this

feature is workload dependent and is limited to TCP applications. Applications such as

backup would see good improvements, but other workloads may not see the same level

of improvement. It is disabled by default and can be enabled using nw_mgr. Please see

the 10 Gigabit driver release notes and the nw_mgr man page on how to enable this

feature and the restrictions to bear in mind when enabling this feature.

The recommendations mentioned here were followed to achieve the results shown in this

article. Card throughput will be affected with configurations other than those recommended.

Please contact an HP representative for additional help in understanding how to best deploy

the AD385A card.