如何使用top命令监控Linux系统性能

作者: 等会再说 | 来源:发表于2019-10-26 22:04 被阅读0次

如何使用top命令监控Linux系统性能
top 命令是是Linux系统中各常用来监控 Linux系统性能的命令之一。你可能经常使用到top命令，使用top命令监控Linux系统性能。而且，你已经知道 top 命令的绝大部分操作，除了一些极个别的操作，例如，top命令的批处理模式。

本教程主要讲解一下什么是top 命令的批处理模式以及如何在批处理模式下运行 top 命令。

什么是 top 命令的批处理模式

批处理模式允许你将 top 命令的输出发送至其他程序或者文件中。

在这个模式中，top 命令将不会接收输入并且持续运行，直到迭代次数达到你用 -n 选项指定的次数为止。

如果你想解决 Linux 服务器上的任何性能问题，你需要正确的理解 top 命令的输出。

如何在批处理模式下运行 top 命令

默认，top 命令按照 CPU 的使用率来排序输出结果，所以当你在批处理模式中运行以下命令时，它会执行同样的操作并打印你指定的行，命令如下：

top -bc | head -35

输出：

top - 06:41:14 up 8 days, 20:24,  1 user,  load average: 0.87, 0.77, 0.81
Tasks: 139 total,   1 running, 136 sleeping,   0 stopped,   2 zombie
%Cpu(s):  0.0 us,  3.2 sy,  0.0 ni, 96.8 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  3880940 total,  1595932 free,   886736 used,  1398272 buff/cache
KiB Swap:  1048572 total,   514640 free,   533932 used.  2648472 avail Mem
PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
     1 root      20   0  191144   2800   1596 S   0.0  0.1   5:43.63 /usr/lib/systemd/systemd --switched-root --system --deserialize 22
     2 root      20   0       0      0      0 S   0.0  0.0   0:00.32 [kthreadd]
     3 root      20   0       0      0      0 S   0.0  0.0   0:28.10 [ksoftirqd/0]
     5 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [kworker/0:0H]
     7 root      rt   0       0      0      0 S   0.0  0.0   0:33.96 [migration/0]
     8 root      20   0       0      0      0 S   0.0  0.0   0:00.00 [rcu_bh]
     9 root      20   0       0      0      0 S   0.0  0.0  63:05.12 [rcu_sched]
    10 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [lru-add-drain]
    11 root      rt   0       0      0      0 S   0.0  0.0   0:08.79 [watchdog/0]
    12 root      rt   0       0      0      0 S   0.0  0.0   0:08.82 [watchdog/1]
    13 root      rt   0       0      0      0 S   0.0  0.0   0:44.27 [migration/1]
    14 root      20   0       0      0      0 S   0.0  0.0   1:22.45 [ksoftirqd/1]
    16 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [kworker/1:0H]
    18 root      20   0       0      0      0 S   0.0  0.0   0:00.01 [kdevtmpfs]
    19 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [netns]
    20 root      20   0       0      0      0 S   0.0  0.0   0:01.35 [khungtaskd]
    21 root       0 -20       0      0      0 S   0.0  0.0   0:00.02 [writeback]
    22 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [kintegrityd]
    23 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [bioset]
    24 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [kblockd]
    25 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [md]
    26 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [edac-poller]
    33 root      20   0       0      0      0 S   0.0  0.0   1:19.07 [kswapd0]
    34 root      25   5       0      0      0 S   0.0  0.0   0:00.00 [ksmd]
    35 root      39  19       0      0      0 S   0.0  0.0   0:12.80 [khugepaged]
    36 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [crypto]
    44 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [kthrotld]
    46 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [kmpath_rdacd]

批处理模式下运行top 命令并按内存使用率排序

在批处理模式中通过运行以下命令按内存使用率对结果进行排序：

top -bc -o +%MEM | head -n 20

输出：

top - 06:42:00 up 8 days, 20:25,  1 user,  load average: 0.66, 0.74, 0.80
Tasks: 146 total,   1 running, 145 sleeping,   0 stopped,   0 zombie
%Cpu(s):  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  3880940 total,  1422044 free,  1059176 used,  1399720 buff/cache
KiB Swap:  1048572 total,   514640 free,   533932 used.  2475984 avail Mem
 PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
 18105 mysql     20   0 1453900 156096   8816 S   0.0  4.0   2:12.98 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
  1841 root      20   0  228980 107036   5360 S   0.0  2.8   0:05.56 /usr/local/cpanel/3rdparty/perl/528/bin/perl -T -w /usr/local/cpanel/3rdparty/bin/spamd --max-children=3 --max-spare=1 --allowed-ips=127.0.0.+
  4301 root      20   0  230208 104608   1816 S   0.0  2.7   0:03.77 spamd child
  8139 nobody    20   0  257000  27108   3408 S   0.0  0.7   0:00.04 /usr/sbin/httpd -k start
  7961 nobody    20   0  256988  26912   3160 S   0.0  0.7   0:00.05 /usr/sbin/httpd -k start
  8190 nobody    20   0  256976  26812   3140 S   0.0  0.7   0:00.05 /usr/sbin/httpd -k start
  8353 nobody    20   0  256976  26812   3144 S   0.0  0.7   0:00.04 /usr/sbin/httpd -k start
  8629 nobody    20   0  256856  26736   3108 S   0.0  0.7   0:00.02 /usr/sbin/httpd -k start
  8636 nobody    20   0  256856  26712   3100 S   0.0  0.7   0:00.03 /usr/sbin/httpd -k start
  8611 nobody    20   0  256844  25764   2228 S   0.0  0.7   0:00.01 /usr/sbin/httpd -k start
  8451 nobody    20   0  256844  25760   2220 S   0.0  0.7   0:00.04 /usr/sbin/httpd -k start
  8610 nobody    20   0  256844  25748   2224 S   0.0  0.7   0:00.01 /usr/sbin/httpd -k start
  8632 nobody    20   0  256844  25744   2216 S   0.0  0.7   0:00.03 /usr/sbin/httpd -k start

对上面命令参数解释信息：

-b：批处理模式选项
-c：打印运行中的进程的绝对路径
-o：指定进行排序的字段
head：输出文件的第一部分
-n：打印前 n 行

批处理模式下运行 top 命令并按照指定的用户进程对结果进行排序

如果你想要按照指定用户进程对结果进行排序请运行以下命令：

top -bc -u mysql | head -n 10

输出：

top - 06:44:58 up 8 days, 20:27,  1 user,  load average: 0.99, 0.87, 0.84
Tasks: 140 total,   1 running, 137 sleeping,   0 stopped,   2 zombie
%Cpu(s): 13.3 us,  3.3 sy,  0.0 ni, 83.3 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  3880940 total,  1589832 free,   885648 used,  1405460 buff/cache
KiB Swap:  1048572 total,   514640 free,   533932 used.  2649412 avail Mem
 PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
 18105 mysql     20   0 1453900 156888   8816 S   0.0  4.0   2:16.42 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid

批处理模式下运行 top 命令并按照处理时间进行排序

在批处理模式中使用以下 top 命令按照处理时间对结果进行排序。该命令可以显示任务从启动以来已使用的总 CPU 时间。

但是如果你想要检查一个进程在 Linux 上运行了多长时间请看接下来的文章：

top -bc -o TIME+ | head -n 20

输出：

top - 06:45:56 up 8 days, 20:28,  1 user,  load average: 0.56, 0.77, 0.81
Tasks: 148 total,   1 running, 146 sleeping,   0 stopped,   1 zombie
%Cpu(s):  0.0 us,  3.1 sy,  0.0 ni, 96.9 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  3880940 total,  1378664 free,  1094876 used,  1407400 buff/cache
KiB Swap:  1048572 total,   514640 free,   533932 used.  2440332 avail Mem
 PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
     9 root      20   0       0      0      0 S   0.0  0.0  63:05.70 [rcu_sched]
   272 root      20   0       0      0      0 S   0.0  0.0  16:12.13 [xfsaild/vda1]
  3882 root      20   0  229832   6212   1220 S   0.0  0.2   9:00.84 /usr/sbin/httpd -k start
     1 root      20   0  191144   2800   1596 S   0.0  0.1   5:43.75 /usr/lib/systemd/systemd --switched-root --system --deserialize 22
  3761 root      20   0   68784   9820   2048 S   0.0  0.3   5:09.67 tailwatchd
  3529 root      20   0  404380   3472   2604 S   0.0  0.1   3:24.98 /usr/sbin/rsyslogd -n
  3520 root      20   0  574208    572    164 S   0.0  0.0   3:07.74 /usr/bin/python2 -Es /usr/sbin/tuned -l -P
   444 dbus      20   0   58444   1144    612 S   0.0  0.0   2:23.90 /usr/bin/dbus-daemon --system --address=systemd: --nofork --nopidfile --systemd-activation
 18105 mysql     20   0 1453900 157152   8816 S   0.0  4.0   2:17.29 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid
   249 root       0 -20       0      0      0 S   0.0  0.0   1:28.83 [kworker/0:1H]
    14 root      20   0       0      0      0 S   0.0  0.0   1:22.46 [ksoftirqd/1]
    33 root      20   0       0      0      0 S   0.0  0.0   1:19.07 [kswapd0]
   342 root      20   0   39472   2940   2752 S   0.0  0.1   1:18.17 /usr/lib/systemd/systemd-journald

批处理模式下运行 top 命令并将结果保存到文件中

如果出于解决问题的目的，你想要和别人分享 top 命令的输出，请使用以下命令重定向输出到文件中：

top -bc | head -35 > top-report.txt
cat top-report.txt

输出：

top - 06:47:11 up 8 days, 20:30,  1 user,  load average: 0.67, 0.77, 0.81
Tasks: 133 total,   4 running, 129 sleeping,   0 stopped,   0 zombie
%Cpu(s): 59.4 us, 12.5 sy,  0.0 ni, 28.1 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem :  3880940 total,  1596268 free,   843284 used,  1441388 buff/cache
KiB Swap:  1048572 total,   514640 free,   533932 used.  2659084 avail Mem
 PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND
  9686 daygeekc  20   0  406132  62184  43448 R  94.1  1.6   0:00.34 /opt/cpanel/ea-php56/root/usr/bin/php-cgi
  9689 nobody    20   0  256588  24428   1184 S   5.9  0.6   0:00.01 /usr/sbin/httpd -k start
     1 root      20   0  191144   2800   1596 S   0.0  0.1   5:43.79 /usr/lib/systemd/systemd --switched-root --system --deserialize 22
     2 root      20   0       0      0      0 S   0.0  0.0   0:00.32 [kthreadd]
     3 root      20   0       0      0      0 S   0.0  0.0   0:28.11 [ksoftirqd/0]
     5 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [kworker/0:0H]
     7 root      rt   0       0      0      0 S   0.0  0.0   0:33.96 [migration/0]
     8 root      20   0       0      0      0 S   0.0  0.0   0:00.00 [rcu_bh]
     9 root      20   0       0      0      0 R   0.0  0.0  63:05.82 [rcu_sched]
    10 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [lru-add-drain]
    11 root      rt   0       0      0      0 S   0.0  0.0   0:08.79 [watchdog/0]
    12 root      rt   0       0      0      0 S   0.0  0.0   0:08.82 [watchdog/1]
    13 root      rt   0       0      0      0 S   0.0  0.0   0:44.28 [migration/1]
    14 root      20   0       0      0      0 S   0.0  0.0   1:22.46 [ksoftirqd/1]
    16 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [kworker/1:0H]
    18 root      20   0       0      0      0 S   0.0  0.0   0:00.01 [kdevtmpfs]
    19 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [netns]
    20 root      20   0       0      0      0 S   0.0  0.0   0:01.35 [khungtaskd]
    21 root       0 -20       0      0      0 S   0.0  0.0   0:00.02 [writeback]
    22 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [kintegrityd]
    23 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [bioset]
    24 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [kblockd]
    25 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [md]
    26 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [edac-poller]
    33 root      20   0       0      0      0 S   0.0  0.0   1:19.07 [kswapd0]
    34 root      25   5       0      0      0 S   0.0  0.0   0:00.00 [ksmd]
    35 root      39  19       0      0      0 S   0.0  0.0   0:12.80 [khugepaged]
    36 root       0 -20       0      0      0 S   0.0  0.0   0:00.00 [crypto]

如何按照指定字段对结果进行排序

在 top 命令的最新版本中，按下 f 键进入字段管理界面。

要使用新字段进行排序，请使用 up/down 箭头选择正确的选项，然后再按下 s 键进行排序。最后按 q 键退出此窗口。

Fields Management for window 1:Def, whose current sort field is %CPU
    Navigate with Up/Dn, Right selects for move then  or Left commits,
    'd' or  toggles display, 's' sets sort.  Use 'q' or  to end!
 PID     = Process Id             nsUTS   = UTS namespace Inode
 USER    = Effective User Name    LXC     = LXC container name
 PR      = Priority               RSan    = RES Anonymous (KiB)
 NI      = Nice Value             RSfd    = RES File-based (KiB)
 VIRT    = Virtual Image (KiB)    RSlk    = RES Locked (KiB)
 RES     = Resident Size (KiB)    RSsh    = RES Shared (KiB)
 SHR     = Shared Memory (KiB)    CGNAME  = Control Group name
 S       = Process Status         NU      = Last Used NUMA node
 %CPU    = CPU Usage
 %MEM    = Memory Usage (RES)
 TIME+   = CPU Time, hundredths
 COMMAND = Command Name/Line
 PPID    = Parent Process pid
 UID     = Effective User Id
 RUID    = Real User Id
 RUSER   = Real User Name
 SUID    = Saved User Id
 SUSER   = Saved User Name
 GID     = Group Id
 GROUP   = Group Name
 PGRP    = Process Group Id
 TTY     = Controlling Tty
 TPGID   = Tty Process Grp Id
 SID     = Session Id
 nTH     = Number of Threads
 P       = Last Used Cpu (SMP)
 TIME    = CPU Time
 SWAP    = Swapped Size (KiB)
 CODE    = Code Size (KiB)
 DATA    = Data+Stack (KiB)
 nMaj    = Major Page Faults
 nMin    = Minor Page Faults
 nDRT    = Dirty Pages Count
 WCHAN   = Sleeping in Function
 Flags   = Task Flags
 CGROUPS = Control Groups
 SUPGIDS = Supp Groups IDs
 SUPGRPS = Supp Groups Names
 TGID    = Thread Group Id
 OOMa    = OOMEM Adjustment
 OOMs    = OOMEM Score current
 ENVIRON = Environment vars
 vMj     = Major Faults delta
 vMn     = Minor Faults delta
 USED    = Res+Swap Size (KiB)
 nsIPC   = IPC namespace Inode
 nsMNT   = MNT namespace Inode
 nsNET   = NET namespace Inode
 nsPID   = PID namespace Inode
 nsUSER  = USER namespace Inode

对 top 命令的旧版本，请按 shift+f 或 shift+o 键进入字段管理界面进行排序。

要使用新字段进行排序，请选择相应的排序字段字母，然后按下回车键排序。

Current Sort Field:  N  for window 1:Def
 Select sort field via field letter, type any other key to return
  a: PID        = Process Id
  b: PPID       = Parent Process Pid
  c: RUSER      = Real user name
  d: UID        = User Id
  e: USER       = User Name
  f: GROUP      = Group Name
  g: TTY        = Controlling Tty
  h: PR         = Priority
  i: NI         = Nice value
  j: P          = Last used cpu (SMP)
  k: %CPU       = CPU usage
  l: TIME       = CPU Time
  m: TIME+      = CPU Time, hundredths
* N: %MEM       = Memory usage (RES)
  o: VIRT       = Virtual Image (kb)
  p: SWAP       = Swapped size (kb)
  q: RES        = Resident size (kb)
  r: CODE       = Code size (kb)
  s: DATA       = Data+Stack size (kb)
  t: SHR        = Shared Mem size (kb)
  u: nFLT       = Page Fault count
  v: nDRT       = Dirty Pages count
  w: S          = Process Status
  x: COMMAND    = Command name/line
  y: WCHAN      = Sleeping in Function
  z: Flags      = Task Flags
 Note1:
   If a selected sort field can't be
   shown due to screen width or your
   field order, the '<' and '>' keys
   will be unavailable until a field
   within viewable range is chosen.
 Note2:
   Field sorting uses internal values,
   not those in column display.  Thus,
   the TTY & WCHAN fields will violate
   strict ASCII collating sequence.
   (shame on you if WCHAN is chosen)

写在最后

如果你是运维人员或者脚本开发人员，可能你已经熟知top命令在批处理中的几种使用方法。如果你不是，你不妨学习一下，可以让你更了解Linux系统中top命令。

如何使用top命令监控Linux系统性能

什么是 top 命令的批处理模式

如何在批处理模式下运行 top 命令

批处理模式下运行top 命令并按内存使用率排序

批处理模式下运行 top 命令并按照指定的用户进程对结果进行排序

批处理模式下运行 top 命令并按照处理时间进行排序

批处理模式下运行 top 命令并将结果保存到文件中

如何按照指定字段对结果进行排序

写在最后

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