Linux Performance Analysis and optimization

Factors affecting the performance of Linux server

1. Operating system level (CPU memory disk I/O performance network bandwidth)

2, program application level

Ii. evaluation criteria of system performance

	Good	Bad	Very poor
Cpu	user% +sys% <70%	user% +sys% =85%	user% +sys% >=90%
Memory	Swap in (SI) =0 Swap out (SI) =0	Per CPU with ten page/s	More Swap in &swap out
Disk	Iowait <20%	Iowait =35%	Iowait >=50%

%user: Represents the percentage of time that the CPU is in user mode.
%sys: Indicates the percentage of time that the CPU is in system mode.
%iowait: Represents the percentage of the CPU waiting for the input and output finish time.
Swap in: That is SI, a page import that represents virtual memory, which is swapped from swap disk to ram
Swap out: That is, so, a page export that represents virtual memory, which is swapped from RAM to swap DISK.

Common system commands
Vmstat, SAR, Iostat, netstat, free, PS, top, etc.
Common Combination Method
Detection of CPU bottlenecks with Vmstat, SAR, Iostat
Use free, vmstat to detect if it is a memory bottleneck
Detect disk I/O bottlenecks with Iostat
Detection of network bandwidth bottlenecks with Netstat

1 Overall performance evaluation ( Uptime command)

2 CPU Performance evaluation

3 Memory Performance evaluation

4 Disk I/O Performance Evaluation

5 Network Performance Assessment

Linux Performance Analysis and optimization