Intel® Ethernet Adapters and Devices User Guide
Receive Side Scaling
When Receive Side Scaling (RSS) is enabled, all of the receive data processing for a particular TCP connection is shared across multiple processors or processor cores. Without RSS all of the processing is performed by a single processor, resulting in less efficient system cache utilization.
LAN RSS
LAN RSS applies to a particular TCP connection.
This setting has no effect if your system has only one processing unit.
LAN RSS Configuration
If your adapter does not support RSS, or if the SNP or SP2 is not installed, the RSS setting will not be displayed. If RSS is supported in your system environment, the following will be displayed:
Port NUMA Node. This is the NUMA node number of a device.
Starting RSS CPU. This setting allows you to set the preferred starting RSS processor. Change this setting if the current processor is dedicated to other processes. The setting range is from 0 to the number of logical CPUs - 1.
Max number of RSS CPU. This setting allows you to set the maximum number of CPUs assigned to an adapter and is primarily used in a Hyper-V environment. By decreasing this setting in a Hyper-V environment, the total number of interrupts is reduced which lowers CPU utilization. The default is 8 for Gigabit adapters and 16 for 10 Gigabit, or faster, adapters.
Preferred NUMA Node. This setting allows you to choose the preferred NUMA (Non-Uniform Memory Access) node to be used for memory allocations made by the network adapter. In addition, the system will attempt to use the CPUs from the preferred NUMA node first for the purposes of RSS. On NUMA platforms, memory access latency is dependent on the memory location. Allocation of memory from the closest node helps improve performance. The Windows Task Manager shows the NUMA Node ID for each processor.
Note: This setting only affects NUMA systems. It will have no effect on non-NUMA systems.
Choosing a value greater than the number of NUMA nodes present in the system selects the NUMA node closest to the device.
Receive Side Scaling Queues. This setting configures the number of RSS queues, which determine the space to buffer transactions between the network adapter and CPU(s).
To change this setting in Intel PROSet:
This setting is found on the Advanced tab of the device’s Device Manager property sheet or in the Adapter Settings panel in Intel PROSet ACU.
To change this setting in Windows PowerShell, use the
Set-IntelNetAdapterSetting -Name "<adapter_name>" -DisplayName "Receive Side Scaling" -DisplayValue "Enabled"
Possible values for this setting are:
1 queue is used when low CPU utilization is required.
2 queues are used when good throughput and low CPU utilization are required.
4 or more queues are used for applications that demand maximum throughput and transactions per second.
Not all settings are available on all adapters.
8, or more, queues are only available when Intel PROSet for Windows Device Manager or Intel PROSet ACU is installed. If Intel PROSet is not installed, only 4 queues are available.
Using 8 or more queues requires the system to reboot.
LAN RSS and Teaming
If RSS is not enabled for all adapters in a team, RSS will be disabled for the team.
If an adapter that does not support RSS is added to a team, RSS will be disabled for the team.
If you create a multi-vendor team, you must manually verify that the RSS settings for all adapters in the team are the same.