How to Check the CPU Usage and Memory Occupancy of Linux Server
As a Linux operation and maintenance engineer, we need to check the CPU usage, memory usage, and bandwidth usage frequently in the system maintenance process and daily work, and analyze the overall operation of the system from the degree of resource usage.
There are many commands to check resource usage on Linux. The CPU, memory, IO, NETWORK and other resource usage can be queried through certain commands. Today Aixi will explain in detail how to check CPU usage and memory usage.
To call the resource viewing command, our first step is to know what the viewing commands are
The following is the TOP command
PID: process identification number
USER: process owner
PR: Process priority
NI: process priority number
VIRT: the virtual memory value occupied by the process
RES: the physical memory value occupied by the process
SHR: Shared memory value used by the process
S: The status of the process, where S means dormant, R means running, and Z means zombie
%CPU: The CPU usage rate occupied by the process
%MEM : Percentage of physical memory occupied by the process
TIME+: The total CPU time occupied by the process since it started
Command: The name of the startup command for the process startup
Free command
View total memory, usage, free, etc.
total: total physical memory size
used: how much has been used
free: how many are available
Shared: the total amount of memory shared by multiple processes
Buffers/cached: the size of the disk cache
Vmstat command
Procs (process):
r: The number of processes in the run queue. This value can also determine whether to increase the CPU. (Long term greater than 1)
b: number of processes waiting for IO
Memory (memory):
swpd: use virtual memory size
free: free physical memory size
buff: memory size used as buffer
cache: memory size used as cache
Swap：
si: The size written from the swap area to the memory per second, transferred from the disk to the memory
so: The memory size written to the swap area per second, transferred from the memory to the disk
IO：
bi: the number of blocks read per second
bo: number of blocks written per second
system:
in: Number of interrupts per second, including clock interrupts.
cs: The number of context switches per second.
CPU (in percent):
us: user process execution time percentage (user time)
sy: Kernel system process execution time percentage (system time)
wa: IO waiting time percentage
id: percentage of idle time
jps command: You can list the process pids of all java applications on the machine.
jps [ options ] [ hostid ]
options
-q Output only the VM identifier, excluding class name, jar name, arguments in main method.
-m Output the parameters of the main method.
-l Output the full package name, application main class name, full path name of jar.
-v Output jvm parameters.
-V Outputs the parameters passed to the JVM through the flag file (.hotspotrc file or -XX:Flags= specified file).
-Joption Pass parameters to vm.
ps command: Display the process status of the current system.
Check which processes are running and their status, whether the process is terminated, whether the process is dead, the resources occupied by the process, etc.
[root@xxx /]# ps -l
Use the following command to find out the threads with high CPU usage:
ps H -eo user,pid,ppid,tid,time,%cpu,cmd --sort=%cpu
1.linux View the programs that occupy the most memory
ps aux|head -1;ps aux|grep -v PID|sort -rn -k +4|head
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2. View the programs that occupy the most CPU
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ps aux|head -1;ps aux|grep -v PID|sort -rn -k +3|head
I'm Chiwang Aixi, and that's all for today's sharing. I hope it will be helpful to friends in need. See you next time!