RED HAT ENTERPRISE LINUX

Managing
Tuning Profiles

Manage tuning profiles

CIS126RH | RHEL System Administration 1
Mesa Community College

A freshly installed RHEL system uses generic kernel and hardware settings suited for general workloads. Tuning profiles optimise dozens of kernel parameters, disk I/O schedulers, CPU governors, and network settings in a single command — adapting the system to its specific role as a database server, virtual machine host, high-throughput network appliance, or power-conscious laptop. The tuned daemon manages these profiles dynamically on RHEL. This skill is tested on the RHCSA exam.

Learning Objectives

1. Explain what tuned is and why tuning profiles matter — Describe the tuned daemon, what kernel parameters profiles adjust, and when to select a non-default profile
2. Install and enable tuned — Install the tuned package, enable the service, and confirm it is running
3. List and select tuning profiles — Use tuned-adm list to discover available profiles and tuned-adm profile to apply one
4. Verify and recommend profiles — Use tuned-adm active to confirm the current profile and tuned-adm recommend to get a system-specific suggestion

What is tuned?

tuned is a daemon that applies and manages system performance tuning profiles. It adjusts kernel parameters dynamically based on the active profile and can adapt settings when system usage patterns change.

• Adjusts kernel parameters via sysctl (network buffers, virtual memory, scheduler settings)
• Sets the CPU frequency governor (performance, powersave, schedutil)
• Configures disk I/O schedulers for each block device
• Manages CPU C-state and power state settings
• Applies transparent hugepages policy
• Adjusts IRQ affinity and NUMA settings on multi-socket systems

Installing and Enabling tuned

The tuned package is available in the BaseOS repository and is installed by default on most RHEL 9 configurations.

# Install tuned if not already present
$ sudo dnf install -y tuned

# Enable and start the tuned service
$ sudo systemctl enable --now tuned

# Verify the service is running
$ systemctl status tuned
● tuned.service - Dynamic System Tuning Daemon
     Loaded: loaded (/usr/lib/systemd/system/tuned.service; enabled; preset: enabled)
     Active: active (running) since Mon 2026-05-25 07:00:00 MST; 14 days ago
   Main PID: 1024 (tuned)
      Tasks: 4 (limit: 49152)
     Memory: 13.5M

# Confirm tuned-adm is available
$ tuned-adm --version
tuned 2.21.0

Listing Available Profiles

tuned-adm list shows all available profiles, with the currently active one marked.

$ tuned-adm list
Available profiles:
- accelerated-baseline  - Basic set of optimizations
- balanced              - General non-specialized tuned profile
- desktop               - Optimize for desktop use cases
- hpc-compute           - Optimize for HPC compute workloads
- intel-sst             - Configure Intel Speed Select Technology
- latency-performance   - Optimize for deterministic performance
- network-latency       - Optimize for lowest network latency
- network-throughput    - Optimize for highest network throughput
- optimize-serial-console - Optimize for serial console use
- powersave             - Optimize for low power consumption
- throughput-performance - Broadly applicable tuning that provides excellent performance
- virtual-guest         - Optimize for virtual guest environments
- virtual-host          - Optimize for virtual host environments

Current active profile: throughput-performance

Built-in Profiles Reference

Applying a Tuning Profile

tuned-adm profile activates a new profile immediately. The change takes effect at once and persists across reboots.

# Apply the throughput-performance profile
$ sudo tuned-adm profile throughput-performance

# Apply the virtual-guest profile
$ sudo tuned-adm profile virtual-guest

# Apply the powersave profile
$ sudo tuned-adm profile powersave

# Apply a composite profile (multiple profiles merged)
$ sudo tuned-adm profile throughput-performance network-throughput

# Confirm the new profile is active
$ tuned-adm active
Current active profile: throughput-performance

Verifying the Active Profile

After applying a profile, confirm it is active and check whether the system is tuned correctly.

# Show the currently active profile
$ tuned-adm active
Current active profile: throughput-performance

# Verify that all settings in the active profile are applied correctly
$ sudo tuned-adm verify
Verification succeeded, current system settings match the preset profile.
See tuned log file ('/var/log/tuned/tuned.log') for details.

# Show what settings the active profile applies
$ sudo tuned-adm profile-info throughput-performance
Profile name:
throughput-performance

Profile summary:
Broadly applicable tuning that provides excellent performance ...

Profile description:
...

# View the tuned service log for troubleshooting
$ sudo journalctl -u tuned --since today

tuned-adm recommend

tuned can analyse the system hardware and environment and recommend the most appropriate profile — useful on systems whose role is unclear or when first setting up a new server.

# Get a profile recommendation for this system
$ tuned-adm recommend
virtual-guest

# On a bare-metal server it might recommend:
throughput-performance

# On a laptop:
balanced

# Apply the recommended profile in one step
$ sudo tuned-adm profile $(tuned-adm recommend)

Disabling tuned and the off Profile

In some situations — troubleshooting a performance regression, custom manual tuning, or a highly specialised workload — you may need to disable tuned's active management.

# Turn off all tuning — tuned still runs but applies no settings
$ sudo tuned-adm off
Switching to profile 'off'

# Confirm tuned is in the "off" state
$ tuned-adm active
No current active profile.

# Stop and disable the tuned service entirely
$ sudo systemctl disable --now tuned

# Re-enable and re-apply a profile
$ sudo systemctl enable --now tuned
$ sudo tuned-adm profile throughput-performance

Profile File Structure

Profiles are directories containing a tuned.conf file. Understanding the structure helps administrators create custom profiles or understand what a profile does.

# Built-in profiles are in /usr/lib/tuned/
$ ls /usr/lib/tuned/
balanced  latency-performance  network-latency  throughput-performance  ...

# Each profile is a directory with tuned.conf inside
$ ls /usr/lib/tuned/throughput-performance/
tuned.conf

# View what throughput-performance actually sets
$ cat /usr/lib/tuned/throughput-performance/tuned.conf
[main]
summary=Broadly applicable tuning that provides excellent performance

[cpu]
governor=performance
energy_perf_bias=performance
min_perf_pct=100

[vm]
transparent_hugepages=never

[disk]
readahead=>4096

Creating a Custom Profile

Custom profiles allow you to combine and extend built-in profiles with site-specific settings.

# Create a custom profile directory
$ sudo mkdir -p /etc/tuned/my-database

# Create the profile configuration
$ sudo tee /etc/tuned/my-database/tuned.conf <<EOF
[main]
summary=Custom database server profile
include=throughput-performance

[sysctl]
vm.swappiness=10
net.core.somaxconn=65535

[vm]
transparent_hugepages=never
EOF

# The new profile is immediately available
$ tuned-adm list | grep my-database
- my-database          - Custom database server profile

# Apply it
$ sudo tuned-adm profile my-database

Dynamic Tuning

tuned can monitor system activity and automatically adjust settings between profiles based on CPU usage, disk activity, and network traffic — without administrator intervention.

# Enable dynamic tuning in /etc/tuned/tuned-main.conf
$ cat /etc/tuned/tuned-main.conf
[tuned]
dynamic_tuning = 0    # 0 = disabled (default), 1 = enabled

# Enable dynamic tuning
$ sudo sed -i 's/dynamic_tuning = 0/dynamic_tuning = 1/' \
    /etc/tuned/tuned-main.conf
$ sudo systemctl restart tuned

# Check current tuning activity
$ sudo tuned-adm active
$ sudo journalctl -u tuned -f

Choosing the Right Profile

Match the tuning profile to the server's primary workload and environment.

tuned-adm Command Reference

Common Mistakes

Knowledge Check

Answer these before moving to the next slide.

1. What command lists all available tuning profiles on the system and shows which one is currently active?
2. A new database server has just been deployed on bare metal. Write the command to apply the most appropriate tuning profile for this workload.
3. Write the command to confirm which tuning profile is currently active after applying a change.
4. A RHEL system is running as a guest inside a VMware hypervisor. Which tuning profile is most appropriate, and why?
5. After applying a profile, you want to confirm that every setting in the profile has been successfully applied to the running system. What command do you use?
6. The tuned service is not running. Write the two commands needed to enable it now and ensure it starts automatically on future boots.

Knowledge Check — Answers

1. tuned-adm list — displays all available profiles with their descriptions, and shows the currently active profile at the bottom of the output.
2. sudo tuned-adm profile throughput-performance — this profile maximises throughput for server workloads including databases, applying performance CPU governor settings, large network and disk buffers, and disabling transparent hugepages.
3. tuned-adm active — shows the name of the currently active profile. No sudo is needed to read the active profile.
4. The virtual-guest profile. Running as a VM guest means the system shares physical hardware with other VMs via the hypervisor. The virtual-guest profile reduces overhead from features like CPU C-states and disk elevator settings that are unnecessary inside a VM and can interfere with hypervisor scheduling.
5. sudo tuned-adm verify — compares every parameter defined in the active profile against the current system state and reports any discrepancies.
6. One option: sudo systemctl enable tuned (for future boots) and sudo systemctl start tuned (to start now). Preferred single command: sudo systemctl enable --now tuned — the --now flag does both in one step.

Key Takeaways

1. tuned applies sets of kernel parameters optimised for specific workloads. The tuned daemon must be running. Enable it with systemctl enable --now tuned. Each profile bundles dozens of sysctl, CPU governor, disk I/O, and power management settings into one named package.
2. The three core commands are list, profile, and active. tuned-adm list shows available profiles. sudo tuned-adm profile PROFILENAME applies one. tuned-adm active confirms which is running. Changes take effect immediately and persist across reboots.
3. Match the profile to the workload. throughput-performance for servers. virtual-guest for VMs. virtual-host for hypervisors. powersave for energy efficiency. latency-performance for low-latency applications. Use tuned-adm recommend when unsure.
4. Verify after applying with tuned-adm verify. A successful verification confirms every profile setting is correctly applied. On the exam, verification is the step that completes the task.

Graded Lab

• Run systemctl status tuned to confirm tuned is running. If it is not, install it with dnf install tuned and enable it with systemctl enable --now tuned.
• Run tuned-adm list to see all available profiles. Note which profile is currently active.
• Run tuned-adm recommend to see which profile tuned suggests for this system. Compare it to the currently active profile.
• Apply the virtual-guest profile with sudo tuned-adm profile virtual-guest. Confirm with tuned-adm active.
• Run sudo tuned-adm verify to confirm all profile settings are applied correctly.
• Apply the throughput-performance profile and verify it is active. Then view its configuration file at /usr/lib/tuned/throughput-performance/tuned.conf and identify one kernel parameter it sets.

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