# Security Settings And IRQbalance

+ SELinux settings
  + Users are advised to disable SELinux
+ Firewall settings
  + Users are advised to disable firewalld or add permission rules for each service in the TiDB cluster
+ IRQbalance service
  + Users are advised to enable the IRQBalance service

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SELinux settings
Check if SELinux is enabled: Users are advised to disable SELinux.

Firewall settings
Check if the firewalld service is enabled: Users are advised to disable firewalld or add allow rules for each service in the TiDB cluster.

IRQbalance check

Background knowledge
- IRQBalance: Literally interpreted as interrupt balancing, it is a daemon that helps balance the CPU load caused by interrupts across all system CPUs. It avoids situations where a single CPU is overloaded
- Interrupt (IRQ): Every hardware device needs to have some form of communication with the CPU so that the CPU knows what's going on in time, so that the CPU may let things down to deal with an emergency. A hardware device actively interrupting the CPU can be called a hardware interrupt.
- We assign a unique interrupt number and IRQ number to each hardware;
The IRQBalance service allows servers with multiple CPU to effectively balance and manage all kinds of interrupt request. Avoiding the dilemma that some CPUs are very busy and others have nothing to do

Check if the IRQBalance service is enabled: Users are advised to enable the IRQBalance service.