Top (topas), vmstat, and iostat are displayed in Linux and AIX operating systems.

The common parameters of each command are listed in detail. to experiment on your own virtual machine, you need to clearly explain the information that is not listed in each line, as well as the differences between commands on different operating system platforms. For example, the output of top commands in Linux and Aix is different.

Top (Linux System)

The top command is a common performance analysis tool in Linux. It can display the resource usage of various processes in the system in real time, similar to the Windows Task Manager.

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Up: system running time

Load average: the average length of the task queue.

Zomibie: Zombie process. Zombie process thread consumption

CPU (s): 1.7% us CPU usage 1.5% Sy CPU usage in kernel space 0.0% percentage of CPU used by processes that have changed their priorities in Ni user process space 96.8% ID idle CPU percentage 0.0% wa CPU time percentage waiting for Input and Output 0.0% hi 0.0% Si Mem physical memory Buffer: The amount of cache used as the kernel Swap swap Zone Cached: the total number of buffer swap areas.   PR priority Ni: Nice value, negative value indicates high priority, positive value indicates low priority. Total virtual memory used by the virt process, in KB. Virt = swap + Res The size of the physical memory used by the res process, Not swapped out, in KB. Res = code + Data Size of SHR shared memory, in KB Time + total CPU time used by the Process Command command name/command line   The rest are easy to understand, so you don't need to list them one by one.

Topas (under AIX)

The topas Command reports important statistics about the activities in the local system, the actual memory size and the number of write operation system calls.

Vmstat command

The vmstat Command reports statistics about Kernel threads, virtual memory, disks, traps, and CPU activity.

The statistical information within the system range (in all processors) calculates the average value in percentage or calculates its sum.

R: Number of kernel threads in the running queue.

B: Number of kernel threads placed in the waiting queue (waiting for resources, waiting for input/output.

SWPD

Free: idle memory

Buff: CPU kernel Cache

Cache: Switch Cache

In: Device interruption

Sy: System Call.

CS: Kernel thread context switch.

US: Number of users.

Sy: system time.

ID: CPU usage percentage.

Wa: Percentage of CPU idle, during which the system has unfinished disks/nfs I/O.

In the AIX system, vmstat is also used to view memory information.

The available memory of the system you see with vmstat is very small, but in fact your application does not use that much memory, instead it is just divided into applications, it is best to use topas to check the memory used by your application.

Iostat

This command is not available in Linux.

In the AIX System

Reports central processor (CPU) statistics and input/output statistics for the entire system, adapter, tty device, disk, and CD-ROM.

Tin

Displays the total number of characters read by the system for all TTY.

Tout

Displays the total number of characters written to all tty machines.

% USER

Displays the percentage of CPU usage during user-level (Application) execution.

% Sys

Displays the percentage of CPU usage during system-level (kernel) execution.

% Idle

Displays the percentage of time when the CPU is idle and the system does not complete disk I/O requests.

% Iowait

Shows the percentage of time when the system has incomplete disk I/O requests during idle CPU.