Tuning BIOS

Purpose

Configure advanced BIOS settings to improve server performance.

Method

The system memory management unit (SMMU) is an address translation bridge between an I/O device and a bus bridge. It translates a virtual address into a physical address and performs permission control and cache management on memory access, ensuring secure and efficient use of the system memory. The database consumes a large amount of memory and I/O resources while the SMMU increases extra overhead and latency, which deteriorates the system performance. Therefore, enabling the SMMU cannot achieve better performance in database scenarios and disabling the SMMU can help reduce the system complexity and maintenance cost. Therefore, it is recommended that the SMMU is disabled in the BIOS for Kunpeng platforms.

Hardware prefetch is to read instructions and data addresses to the cache in advance by tracing the changes of instructions and data addresses. Hardware prefetch applies to scenarios requiring a large number of sequential reads and writes, while databases mainly use random reads and writes. Therefore, you are advised to disable the prefetch function in the BIOS.

• Disable the SMMU.
  

  Disable the SMMU feature only in non-virtualization scenarios. In virtualization scenarios, enable it.

  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 and press Enter.
  3. Set Support Smmu to Disable.
• Disable hardware prefetching.
  1. On the BIOS, choose Advanced > MISC Config and press Enter.
  2. Set CPU Prefetching Configuration to Disabled, and press F10.