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 the 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 the 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 CentOS/RHEL 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:
- Power-saving profiles
- Performance-boosting profiles
The performance-boosting profiles include profiles that focus on the following aspects:
- Low latency for storage and network
- High throughput for storage and network
- Virtual machine performance
- Virtualization host performance
Tuning Profiles Distributed with CentOS/RHEL 8
| TUNED PROFILE | PURPOSE |
|---|---|
| balanced | Ideal for systems that require a compromise between power saving and performance. |
| desktop | Derived from the balanced profile. Provides faster response of interactive applications. |
| throughput-performance | Tunes the system for maximum throughput. |
| latency-performance | Ideal for server systems that require low latency at the expense of power consumption. |
| network-latency | Derived from the latency-performance profile. It enables additional network tuning parameters to provide low network latency. |
| network-throughput | Derived from the throughput-performance profile. Additional network tuning parameters are applied for maximum network throughput. |
| powersave | Tunes the system for maximum power saving. |
| oracle | Optimized for Oracle database loads based on the throughput-performance profile. |
| virtual-guest | Tunes the system for maximum performance if it runs on a virtual machine. |
| virtual-host | Tunes the system for maximum performance if it acts as a host for virtual machines. |
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 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.