Configuring the BIOS

Purpose

Configure advanced BIOS settings to improve server performance.

• The system storage management unit (SMMU) on the server translates device addresses and isolates devices, playing an important part in virtualization. However, SMMU may compromise performance in a physical machine test scenario, especially in a small-packet network scenario. Therefore, you are advised to disable the SMMU function for higher server performance. In VM scenarios, you need to enable the SMMU to use the PCI passthrough function.
• In this test scenario, prefetch causes cache pollution and increases cache misses. Therefore, you are advised to disable the prefetch function.

Procedure

1. Tune the SMMU.

   There are two methods for disabling the SMMU. Select a proper method based on the scenario.

   Method 1:

   

   Method 1 applies only to physical machine and load balancing scenarios, and does not apply to VM scenarios.

   1. Restart the server and enter the BIOS.

      For details, see "Accessing the BIOS" in TaiShan Server BIOS Parameter Reference (Kunpeng 920 Processor).

   2. Choose Advanced > MISC Config > Support Smmu.

      

   3. Set Support Smmu to Disabled. Press F10 to save the settings and exit. The settings are permanently valid.

      

   Method 2:

   

   Method 2 applies to the tuning of physical machine, load balancing, and VM scenarios. This method uses CentOS 7.6-kernel 4.14 as an example. For other OSs, the method is for reference only.

   1. Log in to the OS and open the grub2-efi.cfg file.

      1	vim /etc/grub2-efi.cfg

   2. Search for the 4.14 field and add iommu.passthrough=1 to the kernel code.

      

   3. Press Esc, type :wq!, and press Enter to save the file and exit.
   4. Check whether the modification is successful.

      1	cat /etc/grub2-efi.cfg | grep iommu.passthrough

   5. Restart the server.
2. Disable CPU prefetch.
   1. Access BIOS Setup Utility.
   2. Choose Advanced > MISC Config > CPU Prefetching Configuration.

      

   3. Set CPU Prefetching Configuration to Disabled, and press F10 to save the configuration and exit (the configuration is permanently valid).