Linux Performance Testing Tool Top explanation

The Linux Performance Testing Tool Top shows the actual CPU usage. By default, it displays the CPU-consuming task information on the server and refreshes every 5 seconds. You can classify them in multiple ways, including PID, time, and memory usage.

 
 

  
  
top - 14:37:24 up 15 days, 22:05, 1 user, load average: 0.08, 0.04, 0.01  
  
  
Tasks: 205 total,   1 running, 204 sleeping,   0 stopped,   0 zombie  
  
  
Cpu(s): 0.2% us, 0.2% sy, 0.0% ni, 99.3% id, 0.3% wa, 0.0% hi, 0.0% si  
  
  
Mem:   8162580k total, 7580368k used,   582212k free,    78780k buffers  
  
  
Swap: 8393952k total,   113092k used, 8280860k free, 6368456k cached   
  
  
PID   USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND                                                           
  
  
19338 doms 16 0   102m 36m 17m S   0 0.5   17:11.34 boe_cmsd                                                          
  
  
19597 doms 16 0   145m 62m 43m S   0 0.8   2:04.02 WIReportServer                                                    
  
  
7395 oracle 16 0   6280 1096 772 R   0 0.0   0:00.01 top                                                               
  
  
1 root      16 0   4752 552 460 S   0 0.0   0:50.07 init    
 
 

Statistical information area
The first five lines are the overall statistics of the system.

The first line is the task queue information, which is the same as the execution result of the uptime command. The Top content of the Linux performance testing tool is as follows:
14:37:24 current time
Up 15 days, system running time, format: minute
1 user current Login user count
Load average: 0.08, 0.04, 0.01 system load, that is, the average length of the task queue. The three values are the average values from 1 minute, 5 minutes, and 15 minutes ago to the present.

Second and Third, information about the process and CPU. When multiple CPUs exist, the content may exceed two rows. The content is as follows:
Tasks: 205 total process count
1. Number of running Processes of running
204 sleeping sleep Processes
0 stopped process count
0 zombie botnets
Cpu (s): 0.2% us CPU usage
0.2% sy CPU usage in kernel space
0.0% percentage of CPU used by processes that have changed their priorities in ni user process space
99.3% id idle CPU percentage
0.3% wa CPU time percentage waiting for Input and Output
0.0% hi hardware interruption
0.0% si software interruption

Mem: 191272 k total physical memory
Total physical memory used by 173656 k used
17616 k free Memory Total
Memory usage of 22052 k buffers as kernel Cache
Swap: 192772 k total number of Swap Areas
Total number of swap areas used by 0 k used
192772 k free swap zone total
The total number of swap areas of the 123988 k cached buffer.
The content in the memory is swapped out to the swap zone and then into the memory, but the used swap zone has not been overwritten,
This value indicates the size of the SWAp zone where the content already exists in the memory.
When the corresponding memory is swapped out again, you do not have to write data to the swap zone.

Detailed information about each process is displayed at the bottom of the statistics area of the Top process information area of the Linux performance testing tool. First, let's take a look at the meaning of each column.
Serial Number Column name meaning
A PID process id
B PPID parent process id
C RUSER Real user name
D UID: User ID of the process owner
E USER: USER Name of the process owner
GROUP name of the owner of the f GROUP process
The terminal name of the g TTY startup process. Processes not started from the terminal are displayed?
H PR priority
I NI nice value. A negative value indicates a high priority, and a positive value indicates a low priority.
The final CPU used by j P is only meaningful in multiple CPU Environments
K % percentage of CPU time used since the last CPU update to the present
L total cpu time used by the TIME process, in seconds
M TIME + the total cpu time used by the process, in the unit of 1/100 seconds
N % MEM percentage of physical memory used by the Process
O total virtual memory used by the VIRT process, in kb. VIRT = SWAP + RES
The SWAP size in the virtual memory used by the p SWAP process, in kb.
The size of the physical memory used by the q RES process, Not swapped out, in kb. RES = CODE + DATA
The physical memory occupied by the r CODE executable CODE, in kb.
Physical memory occupied by other parts (DATA Segment + stack) except the executable code of s DATA, in kb
T SHR shared memory size, in kb
U nFLT page error count
The number of modified pages that the last write to the present by v.
W S Process status.
D = uninterrupted sleep
R = run
S = sleep
T = tracking/stopping
Z = zombie Process
X COMMAND name/COMMAND line
Y WCHAN: if the process is sleep, the system function name in sleep is displayed.
Z Flags task flag, refer to sched. h