常用的性能分析工具

mpstat

查看整个系统/cpu维度的资源占用情况

pidstat

查看进程的资源占用情况

vmstat

vmstat reports information about processes, memory, paging, block IO, traps, disks and cpu activity. 分析系统的虚拟内存使用情况，也用于分析上下文切换和中断次数。

procs -----------------------memory---------------------- ---swap-- -----io---- -system-- --------cpu--------
 r  b         swpd         free        inact       active   si   so    bi    bo   in   cs  us  sy  id  wa  st
 0  0            0       234176      4473348      2733180    0    0     0    34    1    1   1   1  99   0   0
 0  0            0       234008      4473516      2733184    0    0     0     0 1209 1831   1   0  99   0   0

1. Procs

• r: running or runnable, 就绪队列长度，正在运行或者等待CPU的进程数。
• b: blocked 处于不可中断睡眠状态的进程数

2. Memory

• swpd: the amount of virtual memory used.
• free: the amount of idle memory.
• buff: the amount of memory used as buffers.
• cache: the amount of memory used as cache.
• inact: the amount of inactive memory. (-a option)
• active: the amount of active memory. (-a option)

3. Swap

• si: Amount of memory swapped in from disk (/s).
• so: Amount of memory swapped to disk (/s).

4. IO

• bi: Blocks received from a block device (blocks/s).
• bo: Blocks sent to a block device (blocks/s).

5. System

• in: The number of interrupts per second, including the clock. interrupt 每秒中断次数。
• cs: The number of context switches per second. context switch,每秒上下文切换次数。

6. CPU

• us: Time spent running non-kernel code. (user time, including nice time)
• sy: Time spent running kernel code. (system time)
• id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
• wa: Time spent waiting for IO. Prior to Linux 2.5.41, included in idle.
• st: Time stolen from a virtual machine. Prior to Linux 2.6.11, unknown.

模拟压力工具stress

stress --cpu 1 timeout 600: 模拟一个CPU使用率100%的进程

stress -i 1 --timeout 600: 模拟IO压力，不停的执行rsync

stress -c 8 --timeout 600: 模拟8个进程