Concept
Top,display Linux tasks, that is: Show Linux processes/tasks.
A usage within Linux
Top
This command means: "Resource usage per process" is displayed. In our performance testing process, we often need to use this command to view the load status of the server.
An introduction to the fields in the output list line 1th
Line 1th |
Note |
16:33:23 |
Current time |
|
Up 5:58 |
The system has been running for 5 hours and 58 minutes. |
If the machine is running for more than 24 hours, Then "N Days" will appear on the left. |
4 Users |
Number of currently logged on users |
|
Load Average |
System load |
The three values are: 1 minutes, 5 minutes, 15 minutes ago to the current average of system load |
Line 2nd
Line 2nd –tasks |
Note |
Total |
Total number of processes 150 |
|
1 Running |
Running Processes 1 |
|
149 Sleeping |
Process of sleep 159 |
|
0 stopped |
The process of stopping |
|
0 Zombie |
Zombie Process |
|
Line 3rd
Line 3rd –cpu (s) |
Note |
0.2%us |
User space consumption CPU percentage (user usage) |
|
0.2%sy |
CPU Percentage of kernel space (System usage) |
If it is too high, it indicates a long system call, such as frequent IO operations |
0.0%ni |
CPU percentage of processes that have changed priority in user process space |
|
99.6%id |
Percentage of idle CPU |
|
0.0%wa |
Percentage of CPU time waiting for input and output |
|
0.0%hi |
Hard Interrupt |
IO Interrupt |
0.0%si |
Soft interrupt |
Network outage |
0.0%st |
Percentage of time that the virtual CPU waits for the actual CPU |
Full Name: Steal time A high steal value may mean that the host vendor sells the virtual machine over the server over and over again. If you upgrade a virtual machine and the steal value is not down, you should look for another service provider. A low steal value means that your application works well on the current virtual machine. Your virtual machine responds faster because your virtual machines don't often compete fiercely with other virtual machines for CPU time. This also implies that your hosting provider does not sell virtual services over an excessive amount, which is definitely a good thing. |
Line 4th
Line 4th –mem |
Note |
2061556 k Total |
Total Physical Memory |
|
1626384 K Used |
Total amount of physical memory used |
|
435172 k Free |
Amount of free memory |
|
56504 K Buffers |
Amount of memory used as the kernel buffer |
"Buffer" is called "buffering" "Buffer is the data that is about to be written to disk, and the data is stored intact." |
Line 5th
Line 5th –swap |
Note |
0k Total |
Total Swap Area |
|
0k used |
Total number of swap areas used |
|
0k Free |
Total Free Swap Area |
|
173428k Cached |
Total number of swap areas cached |
"Cache" is called "Caching" "The cache is the data being read from the disk and waiting to be used." |
The so-called 6th line
Line 6th – Process information |
Note |
Pid |
Process ID |
PPID: Parent Process ID |
USER |
User name of the process owner |
UID: User ID of the process owner |
PR |
Priority level |
|
NI |
Nice value |
A negative value indicates a high priority, Positive values indicate low priority |
VIRT |
Total amount of virtual memory used by the process, in kilobytes |
Virt=swap+res |
Res |
The amount of physical memory that the process uses, not swapped out, in kilobytes |
Res=code+data |
Shr |
Shared memory size, in kilobytes |
|
S |
Process status |
d= non-disruptive sleep state R= Run S= Sleep t= Tracking/Stopping z= Zombie Process |
%cpu |
CPU time consumption percentage last updated to current |
|
%MEM |
Percentage of physical memory used by the process |
|
time+ |
Total CPU time used by the process, Unit 1/100 sec |
|
COMMAND |
Command name/command line |
|
Linux operating system-command-top