How to view the average load on a Linux machine

What is the average machine load?

The number of processes queued for CPU processing during a specific time interval, the more processes queued, the slower CPU processing, and the average load on the machine

How do I measure whether the current system is overloaded?
If the current number of active processes on each CPU (which can be calculated by the number of CPU cores) is not greater than 3, the system performs well,
Not greater than 4, which means that it can accept
If more than 5, the system performance problem is serious

The recommended set of strict alarm values is: The number of CPU cores
For example: The number of CPU cores is 2, then set the alarm value to 2
(This setting is reasonable, because not every application supports multi-CPU and multi-core)

When do I need to see the load on my machine?

When your system request is slow and unbearable.

How to view? Common commands:

UpTime: It shows the number of active user processes and the so-called average load indicator (load average) since the last system restart.

11:38:54	Current time
Up 708 days	System Run time
2 users	Number of currently logged on users
Load average:0.08, 0.02, 0.01	System load, which is the average length of the task queue. The three values were 1 minutes, 5 minutes, and 15 minutes ago to the present average.

Top: Dynamic Display

1. The first line is the task queue information

Results of execution with uptime command:

[Email protected] ~]# uptime

13:22:30 up 8 min, 4 users, Load average:0.14, 0.38, 0.25

The contents are as follows:

12:38:33	Current time
Up 50days	System run time, format last: minutes
1 user	Number of currently logged on users
Load average:0.06, 0.60, 0.48	System load, which is the average length of the task queue. The three values were 1 minutes, 5 minutes, and 15 minutes ago to the present average.

2. Second to third behavioral process and CPU information

When there are multiple CPUs, the content may be more than two lines. The contents are as follows:

tasks:29 Total	Total number of processes
1 Running	Number of processes that are running
Sleeping	Number of processes for sleep
0 stopped	Number of processes stopped
0 Zombie	Number of zombie processes
Cpu (s): 0.3% US	Percentage of CPU occupied by user space
1.0% Sy	Percentage of CPU consumed by kernel space
0.0% ni	CPU percentage of processes that have changed priority in user process space
98.7% ID	Percentage of idle CPU
0.0% WA	Percentage of CPU time waiting for input and output
0.0% hi
0.0% si

3.45th Behavior Memory information.

The contents are as follows:

MEM:191272K Total	Total Physical Memory
173656k used	Total amount of physical memory used
17616k Free	Total Free Memory
22052k buffers	Amount of memory to use as the kernel cache
SWAP:192772K Total	Total Swap Area
0k used	Total number of swap areas used
192772k Free	Total Free Swap Area
123988k Cached	The total amount of buffer swap area. The in-memory content is swapped out to the swap area and then swapped in to memory, but the used swap area has not been overwritten, which is the size of the swap area where the content already exists in memory . When the corresponding memory is swapped out again, it is no longer necessary to write to the swap area.

Two. Process information

Column Name	Meaning
Pid	Process ID
PPID	Parent Process ID
Ruser	Real User Name
Uid	User ID of the process owner
USER	User name of the process owner
GROUP	Group Name of Process owner
Tty	The terminal name of the startup process. Processes that are not started from the terminal are displayed as?
PR	Priority level
NI	Nice value. Negative values indicate high priority, positive values indicate low priority
P	Last CPU used, only meaningful in multi-CPU environment
%cpu	CPU time consumption percentage last updated to current
Time	Total CPU time used by the process, in seconds
time+	Total CPU time used by the process, Unit 1/100 sec
%MEM	Percentage of physical memory used by the process
VIRT	The total amount of virtual memory used by the process, in kilobytes. Virt=swap+res
SWAP	The size, in kilobytes, of the virtual memory that the process is using, swapped out.
Res	The size, in kilobytes, of the physical memory that the process used and was not swapped out. Res=code+data
CODE	The amount of physical memory the executable code occupies, in kilobytes
DATA	The amount of physical memory that is used by parts other than executable code (data segment + stack), in kilobytes
Shr	Shared memory size, in kilobytes
Nflt	Number of page faults
Ndrt	The number of pages that were modified the last time it was written to.
S	Process state. d= non-disruptive sleep state R= Run S= Sleep t= Tracking/Stopping z= Zombie Process
COMMAND	Command name/command line
Wchan	If the process is sleeping, the system function name in sleep is displayed
Flags	Task Flag, reference sched.h

How to view the average load on a Linux machine