The BIOS setting NUMA Nodes per Socket enables the server administrator to specify value between 0 and 4. In this best practice, we increase the number of NUMA Nodes per Socket.. 

Overview

CPUs and local memory banks are referred to as NUMA nodes. For example, in a two-socket server each of the two CPUs has a local memory bank for a total of two NUMA nodes. When a CPU uses the local memory bank memory access is very fast. However, times are not optimal when a CPU must use a remote memory bank access. Thus, the goal is to keep memory in the local memory bank for the best possible performance. 

AMD servers provide the ability to configure additional NUMA nodes per CPU in BIOS. For example, increasing NUMA Nodes per Socket from the default of setting of 1 to 2 configures two NUMA nodes per local memory bank. This works by logically dividing the local memory bank into two equal parts. The benefit is that now each AMD CPU can use two NUMA nodes. 

In this best practice, the NUMA Nodes per Socket was set to 2. The PowerEdge R7525 server had two sockets, meaning we doubled the number of NUMA nodes from the original configuration of two to four. Additionally, the BIOS setting L3 cache as NUMA Domain was enabled to allow the large L3 cache to be used for NUMA nodes. 

The addition of two NUMA nodes and the use of the L3 cache the goal was to accelerate the four virtualized SQL Server databases. 

Recommendation

Using the NUMA Nodes per Socket and L3 cache as NUMA Domain BIOS show no performance improvements for these metrics:

• New Orders per Minute (NOPM).
• Transactions per Minute (TPM).
• Batch Requests per Second
• Server CPU Utilization.
• PowerMax IOPS.

This best practice of increasing the NUMA Nodes per Socket might be most applicable for consolidated database systems. For this reason, we categorized NUMA Nodes per Socket as a Day 3, fine tuning best practices for consolidated database systems.  

With dedicated production servers that only service one database adding additional NUMA nodes most likely will not add value. 

Implementation Steps

Use the following steps to view/update the NPS and L3 cache as NUMA parameters.

1. Turn on or restart your system. 
2. Press F2 immediately after you see the following message: F2 = System Setup 
   1. Note: If your operating system begins to load before you press F2, wait for the system to finish booting, and then restart your system and try again.
3. On the System Setup Main Menu screen, click System BIOS.
4. Click on Processor Settings.
5. Select the following options:
   1. Select 2/4 (or the value of NPS you would like to update to) from the drop-down list of NUMA nodes per socket parameter
   2. Select Enabled for the parameter L3 cache as NUMA domain
6. After updating the setting, click Back.
7. Click Finish on the System BIOS screen.
8. Click Yes on the saving changes pop up screen, to confirm the update. You will see a Success message upon successful updating of values.
9. Click Finish on the System Setup Main Menu screen.
10. Click Yes to confirm Exit and system reboot.

Additional Resources

Dell Support has BIOS settings for the AMD based servers like the PowerEdge R7525