User Manual

Rev 4.70

Mellanox Technologies

http://www.mellanox.com/page/products_dyn?product_family=32&mtag=windows_sw_drivers

 To improve performance, activate the performance tuning tool as follows:

Step 1. Start the "Device Manager" (open a command line window and enter: devmgmt.msc).

Step 2. Open "Network Adapters".

Step 3. Right click the relevant IPoIB adapter and select Properties.

Step 4. Select the "Advanced" tab

Step 5. Modify performance parameters (properties) as desired.

11.3 Tunable Performance Parameters

The following is a list of key parameters for performance tuning.

• Jumbo Packet

The maximum available size of the transfer unit, also known as the Maximum Transmission Unit

(MTU). For IPoIB, the MTU should not include the size of the IPoIB header (=4B). For example, if

the network adapter card supports a 4K MTU, the upper threshold for payload MTU is 4092B and not

4096B. The MTU of a network can have a substantial impact on performance. A 4K MTU size

improves performance for short messages, since it allows the OS to coalesce many small messages

into a large one.

• Valid MTU values range for an Ethernet driver is between 614 and 9614.

• Valid MTU values range for an IPoIB driver is between 1500 and 4092.

• Receive Buffers

The number of receive buffers (default 1024).

• Send Buffers

The number of sent buffers (default 2048).

• Performance Options

Configures parameters that can improve adapter performance.

• Interrupt Moderation

Moderates or delays the interrupts’ generation. Hence, optimizes network throughput and CPU uti-

lization (default Enabled).

• When the interrupt moderation is enabled, the system accumulates interrupts and sends a single interrupt

rather than a series of interrupts. An interrupt is generated after receiving 5 packets or after 10ms from

the first packet received. It improves performance and reduces CPU load however, it increases latency.

• When the interrupt moderation is disabled, the system generates an interrupt each time a packet is

received or sent. In this mode, the CPU utilization data rates increase, as the system handles a larger

number of interrupts. However, the latency decreases as the packet is handled faster.

• Receive Side Scaling (RSS Mode)

Improves incoming packet processing performance. RSS enables the adapter port to utilize the

multiple CPUs in a multi-core system for receiving incoming packets and steering them to the des-

All devices on the same physical network, or on the same logical network, must have

the same MTU.