RHCSA Rapid Track

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

[root@host ~]$ cat /etc/tuned/tuned-main.conf
...output omitted...
# Dynamicaly tune devices, if disabled only static tuning will be used.
dynamic_tuning = 1
...output omitted...
# Update interval for dynamic tunings (in seconds).
# It must be multiply of the sleep_interval.
update_interval = 10
...output omitted...

You can install and enable the tuned package by using the following commands:

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

The tuned application provides profiles in the following categories:

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

The next table shows a list of the tuning profiles that are distributed with Red Hat Enterprise Linux 9:

The tuned application stores the tuning profiles under the /usr/lib/tuned and /etc/tuned directories. Every profile has a separate directory, and inside the directory the tuned.conf main configuration file and, optionally, other files.

[root@host ~]# cd /usr/lib/tuned
[root@host tuned]# ls
accelerator-performance  hpc-compute          network-throughput       throughput-performance
balanced                 intel-sst            optimize-serial-console  virtual-guest
desktop                  latency-performance  powersave                virtual-host
functions                network-latency      recommend.d
[root@host tuned]$ ls virtual-guest
tuned.conf

A typical tuned.conf configuration file looks as follows:

[root@host tuned]# cat virtual-guest/tuned.conf
#
# tuned configuration
#

[main]
summary=Optimize for running inside a virtual guest
include=throughput-performance

[sysctl]
# If a workload mostly uses anonymous memory and it hits this limit, the entire
# working set is buffered for I/O, and any more write buffering would require
# swapping, so it's time to throttle writes until I/O can catch up.  Workloads
# that mostly use file mappings may be able to use even higher values.
#
# The generator of dirty data starts writeback at this percentage (system default
# is 20%)
vm.dirty_ratio = 30

# Filesystem I/O is usually much more efficient than swapping, so try to keep
# swapping low.  It's usually safe to go even lower than this on systems with
# server-grade storage.
vm.swappiness = 30

The [main] section in the file might include a summary of the tuning profile. This section also accepts the include parameter, for the profile to inherit all the settings from the referenced profile.

This configuration file is useful when creating new tuning profiles, because you can use one of the provided profiles as a basis, and then add or modify the parameters to configure. To create or modify tuning profiles, copy the tuning profile files from the /usr/lib/tuned directory to the /etc/tuned directory and then modify them. If profile directories exist with the same name under the /usr/lib/tuned and /etc/tuned directories, the latter always take precedence. Thus, never directly modify files in the /usr/lib/tuned system directory.

The rest of the sections in the tuned.conf file use the tuning plug-ins to modify parameters in the system. In the previous example, the [sysctl] section modifies the vm.dirty_ratio and vm.swappiness kernel parameters through the sysctl plug-in.

Use the tuned-adm command to change the settings of the tuned daemon. The tuned-adm command queries current settings, lists available profiles, recommends a tuning profile for the system, changes profiles directly, or turns off tuning.

You can identify the currently active tuning profile with the tuned-adm active command.

[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 the custom-created tuning profiles.

[root@host ~]# tuned-adm list
Available profiles:
- accelerator-performance     - Throughput performance based tuning with ...
- balanced                    - General non-specialized tuned profile
- desktop                     - Optimize for the desktop use-case
- hpc-compute                 - Optimize for HPC compute workloads
- intel-sst                   - Configure for Intel Speed Select Base Frequency
- latency-performance         - Optimize for deterministic performance at ...
- network-latency             - Optimize for deterministic performance at ...
...output omitted...
Current active profile: virtual-guest

Use the tuned-adm profile_info command for information about a given profile.

[root@host ~]$ tuned-adm profile_info network-latency
Profile name:
network-latency

Profile summary:
Optimize for deterministic performance at the cost of increased power consumption, focused on low latency network performance
...output omitted..

If no profile is specified, then the tuned-adm profile_info command shows the information for the active tuning profile:

[root@host ~]$ tuned-adm active
Current active profile: virtual-guest
[root@host ~]$ tuned-adm profile_info
Profile name:
virtual-guest

Profile summary:
Optimize for running inside a virtual guest
...output omitted..

Use the tuned-adm profile profilename command to switch to a different active profile 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 recommend command can recommend a tuning profile for the system. The system uses this mechanism to determine the default profile after its installation.

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

To revert the setting changes that the current profile applied, either switch to another profile or deactivate the tuned daemon. Turn off the tuned application tuning activity by using the tuned-adm off command.

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

To manage system performance profiles with the web console, you must log in and escalate privileges. Privilege escalation mode permits the user to execute commands, with administrative privileges, that modify system performance profiles. Because changing tuning profiles modifies some system parameters, you must do it with administrative privileges.

You can switch to the administrative access mode in the web console by clicking the Limited access or the Turn on administrative access buttons. Then, enter your password when prompted. After you escalate privileges, the Limited access button changes to Administrative access. As a security reminder, always toggle back to limited access mode after completing the system task that requires administrative privileges.

As a privileged user, click the Overview menu option in the left navigation bar. The Performance profile field displays the current active profile.

Figure 6.1: Active performance profile

To select a different profile, click the active profile link. In the Change performance profile user interface, scroll through the profile list to select one that best suits the system purpose, and click the Change profile button.

Figure 6.2: Select a preferred performance profile

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