Linux Seven week two lessons (March 20) Notes

Seven weeks two sessions (March 20)
10.6 Monitoring IO Performance
10.7 Free Command
10.8 PS Command
10.9 Viewing network status
10.10 Linux under Grab Bag
Extended TCP three-time handshake four times wave http://www.doc88.com/p-9913773324388.html
Tshark several usages: http://www.aminglinux.com/bbs/thread-995-1-1.html

Installing the package Sysstat will install the Iostat. And SAR are the same package.

%util is the percentage of waiting IO. The hard disk can affect the performance of the CPU. If the hard drive is slow, it will certainly affect the performance of the CPU, and the CPU is no longer fast.

I have seen%util is 99%, which indicates that the disk IO is severely inadequate and can only be replaced at the end.

The disk is busy to see which process is reading and writing. Use Iotop to view.

This command does not need to be installed.

Run Command Iotop

View%util

10.7 Free Command

The second line is, memory. The third line is the swap partition. The main focus is on the second line.

The unit of the number is M, which does not show up.

Add units behind the numbers.

Data from the disk to the CPU needs to be temporarily put into a memory, which is part of the cache. The CPU finishes processing the data and puts it into memory, which is part of the buff.


Total=used+free+buff/cache
Available =free+buff/cache has not been occupied yet.
The available is viewed with free.

10.8 PS Command

Use the most. Check if this process is running.

Same as Ps-elf.

10.9 Viewing network status

10.10 Linux under Grab Bag

Linux Seven week two lessons (March 20) Notes