首先介绍一下 top 命令的使用方法, top 程序提供了运行系统的动态实时视图, 它可以显示系统摘要信息以及当前线程或进程的列表
$ top -h
procps-ng 3.3.12
Usage:
top -hv | -bcHiOSs -d secs -n max -u|U user -p pid(s) -o field -w [cols]-hv Help/Version 两者都是打印版本等帮助信息
在命令行参数中提供以下选项可以改变默认值
-b Batch-mode 非窗口模式的输出
-c Command-line/Program-name 显示进程的 command
-H Threads-mode 线程模式 指示top显示单个线程。如果没有此命令行选项，则显示每个进程中所有线程的总和。窗口模式下可以用“ H”更改
-i Idle-process 空闲任务 当此切换为“关闭”时，自上次更新以来未使用任何CPU的任务将不会显示
-O Output-field-names
-S Cumulative-time 累积模式
-s Secure-mode 安全模式
-d Delay-time 延迟时间
-n 刷新次数
-w 限制列数
默认值如下:
Global-defaults
A - Alt display Off (full-screen)
* d - Delay time 1.5 seconds
* H - Threads mode Off (summarize as tasks)
I - Irix mode On (no, `solaris' smp)
* p - PID monitoring Off (show all processes)
* s - Secure mode Off (unsecured)
B - Bold enable On (yes, bold globally)
Summary-Area-defaults
l - Load Avg/Uptime On (thus program name)
t - Task/Cpu states On (1+1 lines, see `1')
m - Mem/Swap usage On (2 lines worth)
1 - Single Cpu Off (thus multiple cpus)
Task-Area-defaults
b - Bold hilite Off (use `reverse')
* c - Command line Off (name, not cmdline)
* i - Idle tasks On (show all tasks)
J - Num align right On (not left justify)
j - Str align right Off (not right justify)
R - Reverse sort On (pids high-to-low)
* S - Cumulative time Off (no, dead children)
* u - User filter Off (show euid only)
* U - User filter Off (show any uid)
V - Forest view On (show as branches)
x - Column hilite Off (no, sort field)
y - Row hilite On (yes, running tasks)
z - color/mono On (show colors)要想监控 CPU 使用情况, 我们可以观察 top -bi -n 1
以下是命令watch top -bi -n 1的输出
Every 2.0s: top -bi -n 1 MyServer: Fri Oct 18 08:45:14 2019
top - 08:45:14 up 36 days, 1:50, 5 users, load average: 0.07, 0.05, 0.01
Tasks: 146 total, 1 running, 144 sleeping, 1 stopped, 0 zombie
%Cpu(s): 0.1 us, 0.0 sy, 0.0 ni, 99.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 2062096 total, 350188 free, 316304 used, 1395604 buff/cache
KiB Swap: 524284 total, 523764 free, 520 used. 1550992 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND当我开启一个线程空转时
Every 2.0s: top -bi -n 1 MyServer: Fri Oct 18 08:45:55 2019
top - 08:45:55 up 36 days, 1:51, 5 users, load average: 0.12, 0.06, 0.01
Tasks: 148 total, 1 running, 146 sleeping, 1 stopped, 0 zombie
%Cpu(s): 0.1 us, 0.0 sy, 0.0 ni, 99.8 id, 0.0 wa, 0.0 hi, 0.0 si, 0.0 st
KiB Mem : 2062096 total, 339368 free, 327092 used, 1395636 buff/cache
KiB Swap: 524284 total, 523764 free, 520 used. 1540204 avail Mem
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
5595 d 20 0 3100664 33628 24520 S 100.0 1.6 0:04.71 java