Basic Registry Keys

*JumboPacket

eth:1514 IPoIB:4096

The maximum size of a frame (or a packet) that can be sent over the wire. This is also known as the maximum transmission unit (MTU). The MTU may have a significant impact on the network's performance as a large packet can cause high latency.

However, it can also reduce the CPU utilization and improve the wire efficiency. The standard Ethernet frame size is 1514 bytes, but Mellanox drivers support wide range of packet sizes.

The valid values are:

• Ethernet: 600 up to 9600

• IPoIB: 1500 up to 4092

Notes:

• When the register is configured via VF running over Microsoft Hyper-V, the value cannot exceed the value configured in the host.

• All the devices across the network (switches and routers) should support the same frame size. Be aware that different network devices calculate the frame size differently. Some devices include the header, i.e. information in the frame size, while others do not. Mellanox adapters do not include Ethernet header information in the frame size. (i.e when setting *JumboPacket to 1500, the actual frame size is 1514).

*ReceiveBuffers

eth:4096 IPoIB:512

The number of packets each ring receives. This parameter affects the memory consumption and the performance. Increasing this value can enhance receive performance, but also consumes more system memory.

In case of lack of received buffers (dropped packets or out of order received packets), you can increase the number of received buffers.

The valid values are 256 up to 4096.

*TransmitBuffers

eth:2048 IPoIB:2048

The number of packets each ring sends. Increasing this value can enhance transmission performance, but also consumes system memory.

The valid values are 256 up to 4096.

*SpeedDuplex

7

The Speed and Duplex settings that a device supports. This registry key should not be changed and it can be used to query the device capability. Mellanox ConnectX device is set to 7 meaning 10Gbps and Full Duplex.

Note: Default value should not be modified.

MaxNumOfMCList

eth:128 IPoIB:128

The number of multicast addresses that are filtered by the NIC. If the OS uses more multicast addresses than were defined, it sets the port to multicast promiscuous and the multicast addresses are filtered by OS at protocol level.

The valid values are 64 up to 1024.

Note: This registry value is not exposed via the UI.

*QOS

eth:1

Enables the NDIS Quality of Service (QoS) The valid values are:

• 1: enable

• 0: disable

Notes:

• This keyword is only valid for ConnectX-3 when using Windows Server 2012 and above.

• This register cannot be configured via a VF that is running over Microsoft Hyper-V.

RxIntModerationProfile

eth:2 IPoIB:2

Enables the assignment of different interrupt moderation profiles for receive completions. Interrupt moderation can have a great effect on optimizing network throughput and CPU utilization.

The valid values are:

• 0: Low Latency

  Implies higher rate of interrupts to achieve better latency, or to handle scenarios where only a small number of streams are used.

• 1: Moderate

  Interrupt moderation is set to midrange defaults to allow maximum throughput at minimum CPU utilization for common scenarios.

• 2: Aggressive

  Interrupt moderation is set to maximal values to allow maximum throughput at minimum CPU utilization, for more intensive, multi-stream scenarios.

TxIntModerationProfile

eth:1 IPoIB:1

Enables the assignment of different interrupt moderation profiles for send completions. Interrupt moderation can have great effect on optimizing network throughput and CPU utilization. The valid values are:

• 0: Low Latency

  Implies higher rate of interrupts to achieve better latency, or to handle scenarios where only a small number of streams are used.

• 1: Moderate

  Interrupt moderation is set to midrange defaults to allow maximum throughput at minimum CPU utilization for common scenarios.

• 2: Aggressive

  Interrupt moderation is set to maximal values to allow maximum throughput at minimum CPU utilization for more intensive, multi-stream scenarios.