查看服务的CPU利用率

01.获取服务的当前CPU份额（比如httpd）

# systemctl show -p CPUShares httpd.service
CPUShares=1024

注意：每个服务的默认值都为CPUShare = 1024.您可以增加/减少进程的CPU份额。

02.将服务的CPU份额（httpd.service）限制为2000 CPUShares /

# systemctl set-property httpd.service CPUShares=2000
# systemctl show -p CPUShares httpd.service
CPUShares=2000

注意：为服务设置CPUShare时，会创建一个名为service的目录（httpd.service.d），其中包含一个包含CPUShare Limit信息的文件90-CPUShares.conf。 您可以将文件视为：

# vi /etc/systemd/system/httpd.service.d/90-CPUShares.conf 
[Service]
CPUShares=2000  

03.检查服务的所有配置详细信息

# systemctl show httpd
Id=httpd.service
Names=httpd.service
Requires=basic.target
Wants=system.slice
WantedBy=multi-user.target
Conflicts=shutdown.target
Before=shutdown.target multi-user.target
After=network.target remote-fs.target nss-lookup.target systemd-journald.socket basic.target system.slice
Description=The Apache HTTP Server
LoadState=loaded
ActiveState=active
SubState=running
FragmentPath=/usr/lib/systemd/system/httpd.service
....

04.分析服务的关键链（httpd）

# systemd-analyze critical-chain httpd.service
The time after the unit is active or started is printed after the "@" character.
The time the unit takes to start is printed after the "+" character.
httpd.service +142ms
└─network.target @11.168s
└─network.service @9.456s +1.712s
└─NetworkManager.service @8.858s +596ms
└─firewalld.service @4.931s +3.926s
└─basic.target @4.916s
└─sockets.target @4.916s
└─dbus.socket @4.916s
└─sysinit.target @4.905s
└─systemd-update-utmp.service @4.864s +39ms
└─auditd.service @4.563s +301ms
└─systemd-tmpfiles-setup.service @4.485s +69ms
└─rhel-import-state.service @4.342s +142ms
└─local-fs.target @4.324s
└─boot.mount @4.286s +31ms
└─systemd-fsck@dev-disk-by/x2duuid-79f594ad/x2da332/x2d4730/x2dbb5f/x2d85d196080964.service @4.092s +149ms
└─dev-disk-by/x2duuid-79f594ad/x2da332/x2d4730/x2dbb5f/x2d85d196080964.device @4.092s

29.获取服务的依赖项列表（httpd）

# systemctl list-dependencies httpd.service
httpd.service
├─system.slice
└─basic.target
├─firewalld.service
├─microcode.service
├─rhel-autorelabel-mark.service
├─rhel-autorelabel.service
├─rhel-configure.service
├─rhel-dmesg.service
├─rhel-loadmodules.service
├─paths.target
├─slices.target
│ ├─-.slice
│ └─system.slice
├─sockets.target
│ ├─dbus.socket
....

05.按层次列出控制组

# systemd-cgls
├─1 /usr/lib/systemd/systemd --switched-root --system --deserialize 23
├─user.slice
│ └─user-0.slice
│   └─session-1.scope
│     ├─2498 sshd: root@pts/0    
│     ├─2500 -bash
│     ├─4521 systemd-cgls
│     └─4522 systemd-cgls
└─system.slice
├─httpd.service
│ ├─4440 /usr/sbin/httpd -DFOREGROUND
│ ├─4442 /usr/sbin/httpd -DFOREGROUND
│ ├─4443 /usr/sbin/httpd -DFOREGROUND
│ ├─4444 /usr/sbin/httpd -DFOREGROUND
│ ├─4445 /usr/sbin/httpd -DFOREGROUND
│ └─4446 /usr/sbin/httpd -DFOREGROUND
├─polkit.service
│ └─721 /usr/lib/polkit-1/polkitd --no-debug
....

06.根据CPU，内存，输入和输出列出控制组

# systemd-cgtop
Path                                                              Tasks   %CPU   Memory  Input/s Output/s
/                                                                    83    1.0   437.8M        -        -
/system.slice                                                         -    0.1        -        -        -
/system.slice/mariadb.service                                         2    0.1        -        -        -
/system.slice/tuned.service                                           1    0.0        -        -        -
/system.slice/httpd.service                                           6    0.0        -        -        -
/system.slice/NetworkManager.service                                  1      -        -        -        -
/system.slice/atop.service                                            1      -        -        -        -
/system.slice/atopacct.service                                        1      -        -        -        -
/system.slice/auditd.service                                          1      -        -        -        -
/system.slice/crond.service                                           1      -        -        -        -
/system.slice/dbus.service                                            1      -        -        -        -
/system.slice/firewalld.service                                       1      -        -        -        -
/system.slice/lvm2-lvmetad.service                                    1      -        -        -        -
/system.slice/polkit.service                                          1      -        -        -        -
/system.slice/postfix.service                                         3      -        -        -        -
/system.slice/rsyslog.service                                         1      -        -        -        -
/system.slice/system-getty.slice/getty@tty1.service                   1      -        -        -        -
/system.slice/systemd-journald.service                                1      -        -        -        -
/system.slice/systemd-logind.service                                  1      -        -        -        -
/system.slice/systemd-udevd.service                                   1      -        -        -        -
/system.slice/webmin.service                                          1      -        -        -        -
/user.slice/user-0.slice/session-1.scope                              3      -        -        -        -