Linux process and Job management

Function of kernel: process management, file system, network function, memory management, driver, security function

Process: A copy of a running program that has a life cycle

Fixed format for Linux kernel storage process information: task struct

Linked list of task struct components for multiple tasks: Task List

Process creation:

Init

Parent-child Relationship

Process: all created by its parent process

Process priority:

0-139:

1-99: Real-time priority

100-139: Static priority (the smaller the number, the higher the priority)

Nice value: -20,19

Process Memory:

Page frame: Pages box for storing page data

Store page

Mmu:memory Management Unit

Ipc:inter Process Communication

On the same host:

Signal, shm:shared memory, Semerphor

On different hosts:

Rpc:remote procecure Call, Socket:

Linux kernel: Preemptive multi-tasking

Process Type:

Daemon: A process initiated during a system boot process that is not related to a terminal

Foreground process: terminal-related, process initiated through terminal

Note: You can also send the foreground-initiated process to the background to run in daemon mode.

Process Status:

Operating state: Running

Ready state: Readiness

Sleep state:

Interruptible: interruptable

Non-disruptive: uninterruptable

Stop state: Paused in memory, but not dispatched unless manually initiated; stopped

Zombie State: Zombie

Classification of processes:

Cpu-bound

Io-bound

Tools for viewing and managing Linux processes: Pstree, PS, Pidof, Pgrep, Top, htop, glance, Pmap, Vmstat, Dstat, Kill, Pkill, job, BG, FG, Nohup

Pstree command:

Pstree-display a tree of processes

Ps:process State

Ps-report a snapshot of the current processes

Information about each process in the Linux system is stored in each file in the/proc/pid directory

PS [OPTION] ...

Options: Support two styles

Common combination: aux

U: Display of process status information in user-centric organization

A: terminal-related processes

X: Terminal-independent processes

~]# PS aux

USER PID%cpu%MEM VSZ RSS TTY STAT START time COMMAND

Vsz:virtual memory SiZe, set of virtual memories

Rss:resident Size, resident memory set

STAT: Process Status

R:running

S:interruptable sleeping

D:uninterruptable sleeping

t:stopped

Z:zombie

+: Foreground process

L: Multithreaded Process

N: Low-priority process

<: high-priority process

S:session leader

Common combination:-ef

-e: Show All Processes

-F: Display full format program information

Common combination:-EFH

-F: Show process information in full format

-H: Show process-related information in process-level format

Common combination:-eo, Axo

-eo Pid,tid,class,rtprio,ni,pri,psr,pcpu,stat,comm

Axo Stat,euid,ruid,tty,tpgid,sess,pgrp,ppid,pid,pcpu,comm

Ni:nice value

Pri:priority, priority

Psr:processor, CPU

Rtprio: Real-time priority

Pgrep, Pkill:

pgrep [Options] Pattern

Pkill [Options] Pattern

-U uid:effective User

-U uid:real User

-T terminal: processes associated with the specified terminal

-L: Show process name

-A: Displays the process name in full format

-P PID: Displays a list of processes whose parent process is specified for this purpose

Pidof:

Get its PID based on the process name

Top

There are many built-in commands:

Sort:

P: Percentage of CPU occupied

M: Percentage of memory occupied

T: Cumulative Occupy CPU duration

The first message shows:

Uptime information: l command

Tasks and CPU information: T command

CPU Display: 1 (digital)

Memory Information: M command

Exit Command: Q

Modify Refresh time interval: s

Terminates the specified process: K

Options:

-D #: Specifies the refresh interval, which defaults to 3 seconds

-B: In batch mode

-N #: Shows how many batches

Htop command:

Options:

-D #: Specify the delay time

-U UserName: Displays only the processes of the specified user

-S Colomn: Sorting in the specified field

Command:

S: Track system calls for selected processes

L: Displays the list of files opened by the selected process

A: Binds the selected process to a specified CPU core

T: Show Process Tree

Vmstat command:

Vmstat [Options] [delay [count]]

Procs:

R: Number of processes waiting to run

B: The number of processes in the non-interruptible sleep state (the length of the blocked queue)

Memory

SWPD: Total amount of swap memory used

Free: Total Idle physical memory

Buffer: The total amount of memory used for buffer

Cache: The total amount of memory used for the cache

Swap

SI: Data rate for data entry into swap (KB/S)

So: Data rate from swap (KB/S)

Io:

BI: The rate at which data is read into the system from the block device; (kb/s)

Bo: The rate at which data is saved to a block device

System

In:interrupts, Interrupt rate

Cs:context switch, process switching rate

Cpu:

US, SY, ID, WA, ST

Options:

-S: Show memory statistics

PMAP command:

Pmap-report memory Map of a process

PMAP [options] pid [...]

-X: Displays detailed format information;

Another implementation:

# Cat/proc/pid/maps

Glances command:

glances [-BDEHMNRSVYZ1] [-B bind] [-C Server] [-C conffile] [-P port] [-p password] [--password] [-t refresh] [-f file] [- O Output]

Built-in commands:

A Sort processes automatically l Show/hide logs

C Sort processes by CPU% b Bytes or bits for network I/O

M Sort processes by mem% W Delete warning logs

P Sort processes by name X Delete Warning and critical logs

I Sort processes by I/O rate 1 Global CPU or PER-CPU stats

d show/hide disk I/o stats h show/hide

F show/hide File system stats T View network I/O as combination

n show/hide Network stats u View Cumulative network I/O

s show/hide Sensors stats Q Quit (ESC and ctrl-c also work)

Y show/hide hddtemp Stats

Common options:

-B: Display nic data rate in bytes

-D: Turn off the disk I/O module

-f/path/to/somefile: Setting the input file location

-O {html| CSV}: Output format

-M: Disable Mount Module

-N: Disable network module

-T #: Delay time interval

-1: Each CPU related data is displayed separately

Run the glances command in C/s mode:

Service mode:

Glances-s-B ipaddr

IPADDR: Indicates which address is listening on this machine

Client mode:

Glances-c ipaddr

IPADDR: Server-side address to connect to

Dstat command:

Dstat [-AFV] [options:] [Delay [Count]]

-C: Display CPU-related information

-C #,#,..., Total

-D: Show disk-related information

-D Total,sda,sdb,...

-G: Display page related statistics

-M: Display Memory related statistics

-N: Display network-related statistics

-P: Show process-related statistics

-R: Displays statistics related to IO requests

-S: Show swapped related statistics

--tcp

--udp

--unix

--raw

--socket

--ipc

--TOP-CPU: Show CPU-intensive processes

--top-io: Show most io-intensive processes

--top-mem: Show the most memory-intensive processes

--top-lantency: Show the process with the most delay

Kill command:

Sends a control signal to the process for process management

Show current system available signals:

# kill-l

# Man 7 signal

Common signals:

1) SIGHUP: No need to close the process and let it reread the configuration file

2) SIGINT: Abort the running process, equivalent to CTRL + C

9) SIGKILL: Kill the Running process

SIGTERM: Terminating a running process

) Sigcont

SIGSTOP)

How to specify the signal:

(1) Digital identification of the signal; 1, 2, 9

(2) Signal complete name; SIGHUP

(3) abbreviated name of the signal; HUP

Signal to process: kill [-signal] PID ...

Terminates all processes under "name": Killall [-signal] Program

Job Control for Linux

Front-end operation: Start with terminal and occupy terminal after startup

Background jobs: Can be started through the terminal, but after starting to run in the background (release terminal)

How do I get my job running in the background?

(1) Operations in operation: CTRL + Z

(2) Jobs not yet started: # COMMAND &

This type of job is sent to the background, but it is still relevant to the terminal; If you want to send to the background, peel off the relationship with the terminal:

# Nohup COMMAND &

View All jobs:

# jobs

Job Control:

# FG [[[%]job_num]: Bring the specified background job back to the foreground

# BG [[%]job_num]: Allow jobs sent to the background to continue running in the background

# Kill [%job_num]: terminates the specified job

Process Priority tuning:

Static priority: 100-139

The nice value is 0 when the process is started by default, and the priority level is 120

Nice command:

Nice [OPTION] [COMMAND [ARG] ...]

Renice command:

Renice [-n] Priority pid ...

View:

PS Axo Pid,comm,ni

This article is from the "Ricky Technology Blog" blog, make sure to keep this source http://r1cky.blog.51cto.com/10646564/1773861

Linux process and Job management