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This article mainly explains "simple analysis of startup performance of Linux system". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "simple analysis of startup performance of Linux system".

Systemd-analyze is a tool for analyzing startup performance, which is used to analyze service time consumption at startup. The default shows that startup is the time consumed by the kernel and user space:

The code is as follows:

[root@localhost~] # systemd-analyze

Startupfinishedin818ms (kernel) + 6.240s (initrd) + 32.979s (userspace) = 40.038s

It has the same effect as using the systemd-analyzetime command.

(1) View the detailed startup time consumed by each service

View the detailed startup time consumed by each service through the systemd-analyzeblame command:

The code is as follows:

[root@localhost~] # systemd-analyzeblame

30.852siscsi.service

16.994skdump.service

10.871sboot.mount

...

103mssystemd-sysctl.service

101msdatapool.mount

(2) View the time-consuming service tree table

The systemd-analyzecritical-chain command prints a heavily time-consuming service tree, sorted by the time consumed by startup, and the more time is consumed, the more time comes first. @ is followed by the time the service is activated or started, and after the + sign, the time it takes to start the service. Personal understanding @ is the time from the system boot to the service startup, is a relative time consumption, + is the service startup time consumption, is an absolute time consumption.

The code is as follows:

[root@localhost~] # systemd-analyzecritical-chain

Thetimeaftertheunitisactiveorstartedisprintedafterthe "@" character.

Thetimetheunittakestostartisprintedafterthe "+" character.

Multi-user.target@32.976s

└─ kdump.service@15.981s+16.994s

└─ network.target@15.980s

└─ NetworkManager.service@15.069s+54ms

└─ firewalld.service@14.532s+535ms

└─ basic.target@14.532s

└─ sockets.target@14.532s

└─ dbus.socket@14.532s

└─ sysinit.target@14.527s

└─ systemd-update-utmp.service@14.524s+2ms

└─ systemd-tmpfiles-setup.service@14.456s+67ms

└─ local-fs.target@14.447s

└─ boot.mount@3.575s+10.871s

└─ systemd-fsck@dev-disk-by\ x2duuid-8c77568b\ x2d7e51\ x2d4e32\ x2dbbdf\ x2ddc12ff737bbf.service@3.348s+226ms

└─ systemd-fsck-root.service@1.237s+152ms

└─ systemd-readahead-replay.service@1.073s+25ms

(3) print analytical drawings and other commands

Systemd-analyzeplot prints a service consumption schedule in svg format, which can be displayed graphically through the browser, which is very intuitive:

The code is as follows:

[root@localhost~] # systemd-analyzeplot > plot.svg

Other parameters:

Systemd-analyzedot uses delimiters to generate the current service

Systemd-analyzedump displays the current service status in a friendly manner

6systemd file type and location

The systemd configuration file is called the unit unit and ends with a different extension depending on the type.

.service system service

.target A set of system services

.automount automatic mount point

A device that can be recognized by the kernel

.mount point

The file or directory of the .path file system

Processes created outside .scope

System process of .slice one-component hierarchical management

.snapshot system service status management

.socket interprocess communication socket

.swap defines a swap file or device

.timer defines a timer.

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