linux命令——iotop

查看CPU使用情况用top，查看I/O使用情况就需要iotop。这个命令是在 kernel v2.6.20中添加，安装的时候要注意内核的版本号。

iotop常用快捷键
1. 左右箭头 --> 改变排序方式，默认是按IO排序
2. r --> 改变排序顺序
3. o --> 只显示有IO输出的进程
4. p --> 进程/线程的显示方式的切换
5. a --> 显示累积使用量
6. q --> 退出

一、安装
     yum install iotop
二、man iotop
NAME
       iotop - simple top-like I/O monitor
SYNOPSIS
       iotop [OPTIONS]
DESCRIPTION
       iotop watches I/O usage information output by the Linux kernel (requires 2.6.20 or later) and displays a table of current I/O usage by processes
       or threads on the system. At least the CONFIG_TASK_DELAY_ACCT and CONFIG_TASK_IO_ACCOUNTING options need to be  enabled  in  your  Linux  kernel
       build configuration, these options depend on CONFIG_TASKSTATS.
       iotop displays columns for the I/O bandwidth read and written by each process/thread during the sampling period. It also displays the percentage
       of time the thread/process spent while swapping in and while waiting on I/O. For each process, its I/O  priority  (class/level)  is  shown.   In
       addition, the total I/O bandwidth read and written during the sampling period is displayed at the top of the interface.
       Use  the left and right arrows to change the sorting, r to reverse the sorting order, o to toggle the --only option, p to toggle the --processes
       option, a to toggle the --accumulated option, q to quit or i to change the priority of a thread or a process’  thread(s).  Any  other  key  will
       force a refresh.
OPTIONS
       --version
              Show the version number and exit
       -h, --help
              Show usage information and exit
       -o, --only
              Only show processes or threads actually doing I/O, instead of showing all processes or threads. This can be dynamically toggled by press-
              ing o.
       -b, --batch
              Turn on non-interactive mode.  Useful for logging I/O usage over time.
       -n NUM, --iter=NUM
              Set the number of iterations before quitting (never quit by default).  This is most useful in non-interactive mode.
       -d SEC, --delay=SEC
              Set the delay between iterations in seconds (1 second by default).  Accepts non-integer values such as 1.1 seconds.
       -p PID, --pid=PID
              A list of processes/threads to monitor (all by default).
       -u USER, --user=USER
              A list of users to monitor (all by default)
       -P, --processes
              Only show processes. Normally iotop shows all threads.
       -u USER, --user=USER
              A list of users to monitor (all by default)
       -P, --processes
              Only show processes. Normally iotop shows all threads.
       -a, --accumulated
              Show accumulated I/O instead of bandwidth. In this mode, iotop shows the amount of I/O processes have done since iotop started.
       -k, --kilobytes
              Use kilobytes instead of a human friendly unit. This mode is useful when scripting the batch mode of iotop. Instead of choosing the  most
              appropriate unit iotop will display all sizes in kilobytes.
       -t, --time
              Add a timestamp on each line (implies --batch). Each line will be prefixed by the current time.
       -q, --quiet
              suppress some lines of header (implies --batch). This option can be specified up to three times to remove header lines.
              -q     column names are only printed on the first iteration,
              -qq    column names are never printed,
              -qqq   the I/O summary is never printed.
SEE ALSO
       ionice(1), top(1), vmstat(1)
AUTHOR
       iotop was written by Guillaume Chazarain.
       This manual page was started by Paul Wise for the Debian project and is placed in the public domain.