The top command is a common performance analysis tool under Linux that shows the resource usage of each process in real time, such as CPU, memory usage, and so on, similar to the Task Manager of Windows.
1. Command format:
top[选项]
2. Common options:
"top -c" 显示完整的命令行而不只是显示命令名。"top -d" 指定每两次屏幕信息刷新之间的时间间隔。"top -n 3" 指定循环的次数为3次。"top -u 用户名" 指定用户名。"top -p 进程号" 指定进程号。
3. Display Information Analysis:
1) The first line of information content analysis
content |
Description |
11:37:29 |
Current system time |
Up 149 days, 23:47 |
The system has been running continuously for 149 days, 23 hours, 47 minutes. |
1 user |
There are currently 1 users logged into the system |
Load average:0.00, 0.00, 0.00 |
The three numbers behind the load average are 1-minute, 5-minute, and 15-minute loads, respectively. |
2) Second line of information content analysis
content |
Description |
tasks:193 Total |
Total number of processes |
1 Running |
Number of processes that are running |
192 Sleeping |
Number of processes for sleep |
0 stopped |
Number of processes stopped |
0 Zombie |
Number of zombie processes |
3) Third line of information content analysis
content |
Description |
Cpu (s): 0.1%us |
Percentage of CPU occupied by user space |
0.1%sy |
Percentage of CPU consumed by kernel space |
0.0%ni |
CPU percentage of processes that have changed priority in user process space |
99.8%id |
Percentage of idle CPU |
0.0%wa |
Percentage of CPU time waiting for input and output |
0.0%hi |
The total amount of time the CPU spends on hardware terminals |
0.0%si |
The total amount of time the CPU spends on software terminals |
0.0%st |
Steal time |
4) The fourth line of information content analysis
content |
Description |
mem:8062100k Total |
Total Physical Memory |
4158524k used |
Total amount of physical memory used |
3903576k Free |
Total Free Memory |
339492k buffers |
Amount of memory to use as the kernel cache |
5) The fifth line of information content analysis
content |
Description |
swap:8191992k Total |
Total Swap Area |
0k used |
Total number of swap areas used |
8191992k Free |
Total Free Swap Area |
1964908k Cached |
Total Buffer Swap Area |
6) Analysis of the information content of the six lines
content |
Description |
Pid |
Process ID |
USER |
User name of the process owner |
PR |
Priority level |
NI |
A nice value negative indicates a high priority, positive values indicate low priority |
VIRT |
Total amount of virtual memory used by the process, Unit kb,virt=swap+res |
Res |
The amount of physical memory not swapped out by the process, Unit Kb,res=code+data |
Shr |
Shared memory size, in kilobytes |
S |
Process Status: d= non-disruptive sleep state, r= run, s= sleep, t= track/Stop, 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 Learning Note--top Command (command to monitor the status of Linux systems)