# Numa

+ NUMA Binding
  + Definition: Memory is directly bound to the CPU, and the CPU will only have a short response time if it accesses the physical address of the memory it manages
  + Servers with NUMA architecture, by binding NUMA node, avoid accessing memory across NUMA as much as possible, and improve the performance of tidb-server
  + Use`numactl` command


![left](./student-guide/diagram/02-15-1.png)


![center](./student-guide/diagram/02-15-2.png)

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NUMA is a memory architecture designed for computers with multiple processors. Memory access time depends on the location of the memory relative to the processor. Under NUMA, a processor can access its own local memory faster than non-local memory (memory located on another processor, or shared between processors).

By default, NUMA is enabled in the BIOS, so we can confirm that it is enabled.

On a server with a NUMA schema, the NUMA schema is turned on, which makes it more efficient to justify server resources. There is a performance loss when accessing memory data from non-native NUMA units. We can avoid performance loss caused by accessing resources across NUMA units by binding instance to NUMA units