RHCSA Rapid Track

Objectives

After completing this section, you should be able to optimize system performance by selecting a tuning profile managed by the tuned daemon.

Tuning Systems

System administrators can optimize the performance of a system by adjusting various device settings based on a variety of use case workloads. The tuned daemon applies tuning adjustments both statically and dynamically, using tuning profiles that reflect particular workload requirements.

Configuring Static Tuning

The tuned daemon applies system settings when the service starts or upon selection of a new tuning profile. Static tuning configures predefined kernel parameters in profiles that tuned applies at runtime. With static tuning, kernel parameters are set for overall performance expectations, and are not adjusted as activity levels change.

Configuring Dynamic Tuning

With dynamic tuning, the tuned daemon monitors system activity and adjusts settings depending on runtime behavior changes. Dynamic tuning is continuously adjusting tuning to fit the current workload, starting with the initial settings declared in the chosen tuning profile.

For example, storage devices experience high use during startup and login, but have minimal activity when user workloads consist of using web browsers and email clients. Similarly, CPU and network devices experience activity increases during peak usage throughout a workday. The tuned daemon monitors the activity of these components and adjusts parameter settings to maximize performance during high-activity times and reduce settings during low activity. The tuned daemon uses performance parameters provided in predefined tuning profiles.

Installing and enabling tuned

A minimal Red Hat Enterprise Linux 8 installation includes and enables the tuned package by default. To install and enable the package manually:

[root@host ~]$ yum install tuned
[root@host ~]$ systemctl enable --now tuned
Created symlink /etc/systemd/system/multi-user.target.wants/tuned.service → /usr/lib/systemd/system/tuned.service.

Selecting a Tuning Profile

The Tuned application provides profiles divided into the following categories:

The performance-boosting profiles include profiles that focus on the following aspects:

Managing profiles from the command line

The tuned-adm command is used to change settings of the tuned daemon. The tuned-adm command can query current settings, list available profiles, recommend a tuning profile for the system, change profiles directly, or turn off tuning.

A system administrator identifies the currently active tuning profile with tuned-adm active.

[root@host ~]# tuned-adm active
Current active profile: virtual-guest

The tuned-adm list command lists all available tuning profiles, including both built-in profiles and custom tuning profiles created by a system administrator.

[root@host ~]# tuned-adm list
Available profiles:
- balanced
- desktop
- latency-performance
- network-latency
- network-throughput
- powersave
- sap
- throughput-performance
- virtual-guest
- virtual-host
Current active profile: virtual-guest

Use tuned-adm profile profilename to switch the active profile to a different one that better matches the system's current tuning requirements.

[root@host ~]$ tuned-adm profile throughput-performance
[root@host ~]$ tuned-adm active
Current active profile: throughput-performance

The tuned-adm command can recommend a tuning profile for the system. This mechanism is used to determine the default profile of a system after installation.

[root@host ~]$ tuned-adm recommend
virtual-guest

To revert the setting changes made by the current profile, either switch to another profile or deactivate the tuned daemon. Turn off tuned tuning activity with tuned-adm off.

[root@host ~]$ tuned-adm off
[root@host ~]$ tuned-adm active
No current active profile.

Managing Profiles with Web Console

To manage system performance profiles with Web Console, log in with privileged access. Click the Reuse my password for privileged tasks option. This permits the user to execute commands, with sudo privileges, that modify system performance profiles.

Figure 6.1: Web Console privileged login

As a privileged user, click the Systems menu option in the left navigation bar. The current active profile is displayed in the Performance Profile field. To select a different profile, click the active profile link.

Figure 6.2: Active performance profile

In the Change Performance Profile user interface, scroll through the profile list to select one that best suits the system purpose.

Figure 6.3: Select a preferred performance profile

To verify changes, return to the main System page and confirm that it displays the active profile in the Performance Profile field.

Figure 6.4: Verify active performance profile