September 17 Process management, job management

Processes, running programs, running in their own linear address space

Program: Instruction plus data composition

On a 32-bit host, the 1G kernel is used and the rest belongs to the application

The 32-bit host CPU can handle 32-bit data at the same time, that is, 2 of the 32 power address space, equivalent to 4g address space, so the 32-bit host can support up to 4g of memory.

BSD-style commands do not need to be added-, such as PS

SysV style needs to add-

Fork () system call

Any process that wants to create its own subprocess needs to initiate a fork call that can create the same child as herself and address space

Cow mechanism: Copy on writting

The parent and child processes share the same address space, and when the value of either party needs to be changed, it is assumed that the child process is ripe and the parent process creates its own independent address space

Process hangs: The resulting results are stored in the task struck each time you have not finished processing.

Process priority: 0-139

1-99: Dynamic Priority: The larger the number, the higher the priority level

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

Process classification:

CPU Bound:cpu Intensive

I/O bound: Intensive

Status of the process

R Operating state: Running

Sleep state: Sleeping

S can interrupt sleep: interruptible

D Non-disruptive sleep: uninterruptible

Ready state: Runnable

T stop state: Stopped, cannot be scheduled to run

Z Zombie State: Zombie, the parent process is dead and it's not released yet.

S:session leader

+: Foreground process, occupy a terminal

L: Multithreaded Process

<: high-priority processes

N: Low-priority process

Linux is Lwp:light WEight Process

For Linux, a process is a thread, and a thread is a process.

Process view and management tools: TOP,PSTREE,PS,PIDOF,PGREP,PKILL,HTOP,GLANCES,PMAP,DSTAT,IOSTAT,SAR,KILL,JOB,BG,FG

Pstree:-p can display the process ID

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Ps:process Stat

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User: Owner,

PID: Process ID

%CPU:% of CPU

%MEM:% of memory

VSZ: Virtual Memory Set: The amount of space occupied by the linear address space

RSS: Resident Memory Set: The size of the data that cannot be swapped to swap space

TTY: Terminal

STAT: The status of the process, which says

Start: Startup time

Time: Cumulative length

Command: Which commands are started, [] indicates kernel threads

Common formats:

Aux:a related to terminal, x independent of terminal, u user-centric

-ef:e: Show all information, F rich format information

-efh:f Show additional information, h Show hierarchical relationships, view parent-child process relationships

AXO: Customizing the information that needs to be displayed, O: Custom Fields

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Pgrep: Used to filter processes

-U: Show only processes running as specified user

-L: Show process name

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PIDOF: Shows the process number occupied by a program

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Top: Dynamic display of the first row and uptime,

Parameters

-b:batch: Batch-time display

-N: Specify the display several times

-D: Delay time interval

Action commands

P is sorted by CPU percentage

M Press Memory,

T per CPU cumulative elapsed time

L: Whether the load line is displayed,

T show summary and CPU load

m Displays memory information

Q: Exit

S: Change time delay, default is 3s

K: Terminates the specified process

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1, Top: Current system time: Run often: The current number of users logged into the system: Load status (last 1 minutes, 5 minutes, 15 minutes of load, CPU waiting queue Length)

2. Tasks: Number of processes:

3, CPUs, press 1 key to display the status of each CPU:

Run space CPU scale userspace, kernel code CPU scale System,nice value percentage, idle percentage idel, wait for IO to complete% wait, hardware interrupt processing percent hardwareinterface, Software interrupt processing percent softwareinterface, the time the virtualization was stolen stolen

4, Swap: Virtual memory all space, used space, free space

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PR: Priority

Ni:nice value

VIRT: Virtual Memory Set

RES: Resident Memory Set

SHR: Shared Memory space

S: Status

%cpu: Percentage of CPU occupied

%MEM: Percentage of memory occupied

Time: Cumulative run times

Command: Start commands

Htop

Need to configure Yum source

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Usage

U show only the process of the specified user

s trace the system call initiated by the process, ESC exits

L Show documents opened by the process

T: Hierarchical results display

A sets the inherited CPU affinity

Parameters:

-D #: Delay

-u:user

-S: Sort by field

Vmstat:

Delay count

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R Run Queue Length

B Block Queue Length

Si: rate of data entering swap Kbps

So data out of swap rate Kbps

BI block device read rate Kbps

The rate at which Bo is saved to the block device Kbps

In interrupt rate Kbps

CS Process Switching rate Kbps

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/proc/#接口

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Pmap 1

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Glances Support CS Architecture

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Dstat powerful 650) this.width=650; "title=" image "style=" border-top:0px; border-right:0px; border-bottom:0px; border-left:0px; Display:inline "border=" 0 "alt=" image "src=" http://s3.51cto.com/wyfs02/M00/73/96/wKiom1YBajnBXT4uAAGrnA_ 55sm044.jpg "" 636 "height=" 199 "/>

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Common usage

--TOP-CPU, showing the most CPU-based information

--top-bio, showing the process of the minimum number Blockio

--top-io

--top-mem

--IPC displaying data related to interprocess communication

--raw displaying data about raw packages

--tcp displaying data related to TCP sockets

--UDP displaying data related to UDP sockets

--unix

--socket

Inter-process communication:

Signal: Short message, can man 7 signal or kill-l view

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1 is rereading the configuration file

The signal can be written like this:

1, full write SIGINT

2, abbreviated INT

3. Label 15

Signal to process:

Kill signal Process Number

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Killall httpd program name to close a set of

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I'm going to have to add a D, or I can't.

Job Management

Front Desk: Terminal launch

Background: The job starts with terminal-independent, or hangs to the background after the foreground starts regardless of terminal

When started: Ctrl Z sent to background

When not started: You can command & let the command start in the background, go inside will stopped

The relationship between the stripping process and the terminal:

# nohup Command &

Jobs can view the job in the background: + means the first one out,-indicates the second one comes out

FG 2 can be transferred back to the front desk

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BG: Start up a specified job in the background and let it run in the background

Kill% #终止指定作业

Process Priority tuning:

Adjust with nice value: can only be adjusted, the priority is small

Nice value: -20,19

Priority level: 100,139

Processes that have not been started:

Nice–n n Command

For a process that has started:

Renice–n N PID

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September 17 Process management, job management