Performance Tuning

This section describes how to modify Windows registry parameters in order to improve performance.

To achieve the best performance for Windows, you may need to modify some of the Windows registries.

Registry Tuning

The registry entries that may be added/changed by this “General Tuning” procedure:

• Under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters:

  • Disable TCP selective acks option for better CPU utilization:

    Registry Key	Type	Value
    SackOpts	REG_DWORD	0

• Under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\AFD\Parameters:

  • Enable fast datagram sending for UDP traffic:

    Registry Key	Type	Value
    FastSendDatagramThreshold	REG_DWORD	64K

• Under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Ndis\Parameters:

  • Set RSS parameters:

    Registry Key	Type	Value
    RssBaseCpu	REG_DWORD	1

Enable RSS

Enabling Receive Side Scaling (RSS) is performed by running the following command:

            

            
“netsh int tcp set global rss = enabled”
        

Improving Live Migration

In order to improve live migration over SMB direct performance, please set the following registry key to 0 and reboot the machine:

            

            
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\LanmanServer\Parameters\RequireSecuritySignature
        

Ethernet Performance Tuning

The user can configure the Ethernet adapter by setting some registry keys. The registry keys may affect Ethernet performance.

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

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

2. Open "Network Adapters".

3. Right click the relevant Ethernet adapter and select Properties.

4. Select the "Advanced" tab

5. Modify performance parameters (properties) as desired.

Performance Known Issues

• On Intel I/OAT supported systems, it is highly recommended to install and enable the latest I/OAT driver (download from www.intel.com).

• With I/OAT enabled, sending 256-byte messages or larger will activate I/OAT. This will cause a significant latency increase due to I/OAT algorithms. On the other hand, throughput will increase significantly when using I/OAT.

Ethernet Bandwidth Improvements

To improve Ethernet Bandwidth:

1. Check you are running on the closest NUMA.

   1. In the PowerShell run: Get-NetAdapterRss -Name "adapter name"

      

   2. Validate that the IndirectionTable CPUs are located at the closest NUMA.
      As illustrated in the figure above, the CPUs are 0:0 - 0:7, CPU 0 -7 and the distance from the NUMA is 0, 0:0/0 - 0:7/0, unlike CPU 14-27/32767.

   3. If the CPUs are not close to the NUMEA, change the "RSS Base Processor Number" and "RSS Max Processor Number" settings under the Advance tab to point to the closest CPUs.

      Warning

      For high performance, it is recommended to work with at least 8 processors.

2. Check the Ethernet bandwidth, run ntttcp.exe.

• Server side: ntttcp -r -m 32,*,server_ip

• Client side: ntttcp -s -m 32,*,server_ip

IPoIB Performance Tuning

The user can configure the IPoIB adapter by setting some registry keys. The registry keys may affect IPoIB performance.

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

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

2. Open "Network Adapters".

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

4. Select the "Advanced" tab

5. Modify performance parameters (properties) as desired.

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