Importance of Linux System Fundamental In Technical Documentation Reading

by netman<netman@study-area.org>

August 2016

The Sample Document

https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/pdf/Virtualization_Tuning_and_Optimization_Guide/Red_Hat_Enterprise_Linux-7-Virtualization_Tuning_and_Optimization_Guide-en-US.pdf

The Basic Requirement

English reading Google searching +

Command line & Quoting

Improper line ending

perf kvm --host --guest --guestmodules=guest-modules report -i \ perf.data.kvm --force > analyze

Should be:

perf kvm --host --guest --guestmodules=guest-modules report -i perf.data.kvm \ --force > analyze

Or:

Configuration of sysctl

echo “net.ipv4.conf.all.arp_filter=1” >> /etc/sysctl.conf sysctl -p

It means:

Kernel module management

echo “options vhost_net experimental_zcopytx=1” \ > /etc/modprode.d/vhost_net.conf modprobe –r vhost_net modprobe vhost_net

Actually you should do:

Configuration file path

You have to know about:

• The guest xml path: /etc/libvirt/qemu/guest_name.xml OR • The command to edit guest xml: virsh edit guest_name

Substitute to a number!

Try & Error

virsh memtune virtual_machine --hard-limit size

It is wrong!!

It should be:

Using systemd

Using echo command to change /sys settings will be lost after reboot!

Solutions:

• Put the commands into /etc/rc.local OR • Create a systemd script : vi /etc/systemd/system/set_transparent_hugepages.service [Unit] Description=Disable transparent hugepages After=multi-user.target [Service] ExecStart=/usr/bin/bash -c 'echo never > /sys/kernel/mm/transparent_hugepage/enabled' [Install] WantedBy=graphical.target systemctl enable set_transparent_hugepages.service

Vi/Vim Editing

It requires you using vi or vim!

Grub configuration

It’s talking about modifying kernel options in GRUB:

vi /etc/default/grub GRUB_CMDLINE_LINUX=“… default_hugepagesz=1G hugepagesz=1G hugepages=4 hugepagesz=2M hugepages=1024" grub2-mkconfig -o /boot/grub2/grub.cfg

Using yum

yum list '*numa*' yum install numactl

Command not found!!

You must install it first:

Using locate

It doesn’t show you the full path!

You have to find it out:

Many more…

Thank you!