服务的CPU利用率（分配额）

25. 获取当前某个服务的CPU分配额（如httpd）

# systemctl show -p CPUShares httpd.service

CPUShares=1024

注意：各个服务的默认CPU分配份额=1024，你可以增加/减少某个进程的CPU分配份额。

26. 将某个服务（httpd.service）的CPU分配份额限制为2000 CPUShares/

# systemctl set-property httpd.service CPUShares=2000

# systemctl show -p CPUShares httpd.service

CPUShares=2000

注意：当你为某个服务设置CPUShares，会自动创建一个以服务名命名的目录（如 httpd.service），里面包含了一个名为90-CPUShares.conf的文件，该文件含有CPUShare限制信息，你可以通过以下方式查看该?件：

# vi /etc/systemd/system/httpd.service.d/90-CPUShares.conf

[Service]

CPUShares=2000

27. 检查某个服务的所有配置细节

# 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=TheApache HTTP Server

LoadState=loaded

ActiveState=active

SubState=running

FragmentPath=/usr/lib/systemd/system/httpd.service

....

28. 分析某个服务（httpd）的关键链

# 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-byx2duuid-79f594adx2da332x2d4730x2dbb5fx2d85d196080964.service@4.092s+149ms

└─dev-disk-byx2duuid-79f594adx2da332x2d4730x2dbb5fx2d85d196080964.device@4.092s

29. 获取某个服务（httpd）的依赖性列表

# 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

....

30. 按等级列出控制组

# 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

....

31. 按CPU、内存、输入和输出列出控制组

# systemd-cgtop

PathTasks%CPU MemoryInput/s Output/s

/831.0437.8M--

/system.slice -0.1---

/system.slice/mariadb.service 20.1---

/system.slice/tuned.service 10.0---

/system.slice/httpd.service 60.0---

/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.scope3----