Using Tuned Profiles

Introduction to Tuned

• Tuned is focused on system tuning and optimization.

• Found in the proc directory within the proc pseudo file system.

• Contains tunable parameters that govern various system settings.

• Allows for the modification of the current values of these tunables by echoing new values into files.

System Tuning

• To make it persistent: echo 40 > /proc/sys/vm/swappiness.

• Changing parameters via the proc file system requires expertise.

Purpose of Tuned

• Tuned simplifies the tuning process.

• It is a systemd service designed for easier management.

• Utilizes different profiles suitable for specific workloads.

Profiles in Tuned

• Profiles correspond to various use cases (e.g., virtual guest).

• Example command to show current profiles: tuned-adm list.

• Command to set a specific profile (e.g., for virtualization): tuned-adm profile virtual-guest.

• Each profile includes a configuration file within /etc/tuned/<profile_name>/tuned.conf.

• These configuration files hold critical performance-related settings.

Managing Tuning Information

• Deciding whether to use Tuned or sysctl and the proc file system:

  • Controlled by reapply_sysctl option in /etc/tuned/tuned-main.conf:

  • Set to 1: sysctl settings take precedence in case of conflicts.

  • Set to 0: Tuned settings take precedence.

Creating Custom Profiles

• Custom profiles can be created easily.

• Store these profiles in the directory /etc/tuned/profiles/.

• Each custom profile requires a subdirectory and a tuned.conf file with performance settings.

Demonstration of Tuned Setup

• Install Tuned with: dnf install -y tuned.

• Enable the Tuned service with: systemctl enable --now tuned.

• Check active profiles using: tuned-adm list.

• The current profile, post-installation, is typically set to balanced.

• To ask the system for better profile recommendations: tuned-adm recommend.

  • Example output indicates that virtual-guest might be a better fit.

Adjusting System Parameters

• For adjusting the vm.swappiness parameter:

  • Use command: echo vm.swappiness=33 > /etc/sysctl.d/swappiness.conf.

  • vm.swappiness affects memory handling during low memory conditions:

  • Values near 0: System reduces inactive cache to avoid swapping.

  • Values near 200: System favors moving inactive application memory to swap.

• To activate the new setting use: sysctl -p /etc/sysctl.d/swappiness.conf.

• To verify the setting, you can execute: sysctl -a | grep swappiness.

Largest Number of Sysctl Parameters

• The system can contain a vast number of tunable parameters, for example, 1,068 parameters available for tuning.

Creating and Activating Custom Profile

• To create a profile tagged as my_profile, use the following commands:

  • Create directory: mkdir /etc/tuned/profiles/my_profile

  • Generate configuration file: echo > /etc/tuned/profiles/my_profile/tuned.conf.

    • Shebang and settings headers can be added: sysctl as header and set vm.swappiness=66.

  • Exit interactive prompt when done (indicated by EOF).

Activating the Custom Profile

• Check if the new profile is picked using: tuned-adm list.

• To activate it: tuned-adm profile my_profile.

• Confirm activation via checking the active profile using last line of tuned-adm list.

Final Verification of Parameters

• Check resultant parameter (swappiness in this case) to confirm settings:

  • Use command: sysctl -a | grep swap to see the value of vm.swappiness as 33.

  • The overriding factor is determined by reapply_sysctl settings within tuned-main.conf.

    • If reapply_sysctl is set to 1: sysctl settings take precedence (as explained).

    • Setting reapply_sysctl to 0 causes Tuned settings to dominate, requiring a service restart for changes to take effect.