"Linux_ Notes" Linux process Management (PS)

Learning resources from: www.magedu.com

The learning record process is inevitably error, the example is for reference only, the great god please ignore.

Process Management Related commands:
Ps:process State (Process status)
SYSV Style:-elf
Common Command formats:
Ps-e
Ps-el | Head
ps-elf | Head
Ps-ef (Common)

BSD style: PS aux | Head
A: Display of terminal-related processes (not absolute)
U: Show more information
X: Show non-terminal processes (not absolute)

Display content:
RSS: Resident Memory Set (data that cannot be swapped to hard disk)
VSZ: Virtual Memory Set
Process status (STAT):
D: Non-disruptive sleep
R: Run or ready
S: interruptible Sleep
T: Stop
Z: Zombie

<: high-priority process
N: Low-priority process
+: Processes in the foreground process group
L: Multithreaded Process
S: Session process first Process
[]: Kernel thread

-O: Specify display fields

Ps-o Property1,property2

Ps-axo Pid,comm,ni | Head
PA aux | grep "Bash" (Find process)
Pstree: Show Process Tree
Pgrep: Finding the specified process in grep style
Pgrep-u root bash//root user as host and bash process
Pgrep bash//show only process numbers
PIDOF: Find the process number according to the program name
Top: Monitoring the running status of the process
CPU (s): Average
1: Expand

Command:
M: Sort based on the size of the resident memory
P: Sort by CPU percent usage
T: Sort by cumulative time

L: Show average load and start time
T: whether to display process and CPU status related information
M: whether memory-related information is displayed

C: Whether to display full command line information
Q: Exit Top
K: Terminate a process

Options:
-D: Specify the delay length in seconds
-B: Batch mode (flip screen)
-N #: Total number of batches displayed in batch mode

Vmstat: System Status View command
Vmstat N m: refreshes every n seconds, showing only M
Free: View disk consumption status
Kill
Kill PID: Terminates a process
Kill%jobid: Terminate a job
Killall COMMAND: Terminates all processes under a program

Kill-l: Show all available signals
Important Signals:
1:sighup: Allow a process to reread its configuration file without restarting, and let the new configuration information take effect
2:sigint:ctrl+c: Interrupts a process
9:sigkill: Kill a process
15:sigterm: Terminates a process (default signal)
Specify the mode of the signal:
Signal Number: KILL-1
Signal Name: Kill-sigkill
Signal Name: Kill-kill
Pkill (similar to pgrep)
BG: Background jobs: occupy the command prompt
BG [%]jobid: Start a background job
FG: Foreground job: After startup, release the command prompt, and subsequent operations are completed in the background
FG [%]jobid: Returning a background job to the foreground

Front desk--Backstage:
CTRL + Z: Send the foreground job to the background (the default job status is stop)
Command &: Let commands execute in the background

Jobs: View all jobs in the background
(Job number differs from process number)
+: Command will default action for jobs
-: command to assign a second default action to the job

Uptime:top First line of information

Adjust nice values: (Adjust process priority)
1, Process has started: Renice NI PID
2. Specify a nice value at startup: Nice-n NI COMMAND

Cat/proc/meminfo: Viewing memory information
Cat/proc/pid/maps: Viewing specified process memory information


================= process Management Related concepts ==================

Memory: Linear memory, physical memory
Kernel data structure:
Task struct
Pid:7
Ppid
Name
...
Abbreviation Explanation:
Mmu:memory Management Unit Memory Management Unit
Tlb:translation lookaside Buffer Bypass conversion buffer (block table)
Context Switch: Contextual switching (process switching)
RSS: Resident Memory Set (data that cannot be swapped to hard disk)
VSZ: Virtual Memory Set
Pid:process ID Process Number PPID-parent process Number (init process number 1)
Ipc:inter Process Communication interprocess communication

Process:
Process number
Memory space
User
Parent process
CPU time

Process Execution Features:
Multicore system: One CPU can only execute one process at a time
Parallel programming model (multithreaded model): threads.
(Dividing a process into multiple execution streams (executing entities) to enable a process to run concurrently on multiple CPUs)
Process: Allocating resources
Threads: Shared resources allocated by the process, responsible for running
Issues to be addressed: Sync: Lock ... (Spin Lock)

Process status: Stop, Ready, execute, sleep, zombie (process ended but memory not released)
Sleep state type:
Uninterruptib sleep: Non-disruptive sleeping: external resources required (open file)
Interruptable sleep: Sleeps can be interrupted

Parent-child relationship for a process:
Kernel: (God)
Init: The first process generated by the kernel, which is the parent process for all other processes
Pstree: Show Process Tree

Priority level: 0-139
100-139: Users can control
Nice value: -20~19 corresponds to 100~139,nice value the higher the priority level
(Ordinary users can only adjust the nice value of their own process)
0-99: Can only be adjusted by the kernel

High-priority features:
1. Get more CPU Run time
2, more preferential access to operational opportunities

Process Information Location:/proc (a process number corresponds to a process)
Classification of processes: terminal-related processes, terminal-independent processes

This article from "Not Daze" blog, please make sure to keep this source http://tobeys.blog.51cto.com/10620284/1721980

"Linux_ Notes" Linux process Management (PS)