2.5. Tuned

Tuned is a profile-based system tuning tool that uses the udev device manager to monitor connected devices, and enables both static and dynamic tuning of system settings. Dynamic tuning is an experimental feature and is turned off by default in Red Hat Enterprise Linux 7.

Tuned offers predefined profiles to handle common use cases, such as high throughput, low latency, or power saving. You can modify the Tuned rules for each profile and customize how to tune a particular device. For instructions on how to create custom Tuned profiles, from PowerTOP suggestions, see the section called “Using powertop2tuned”.

A profile is automatically set as default based on the product in use. You can use the tuned-adm recommend command to determine which profile Red Hat recommends as the most suitable for a particular product. If no recommendation is available, the balanced profile is set.

The balanced profile, which is suitable for most workloads, balances energy consumption, performance, and latency. With the balanced profile, finishing a task quickly with the maximum available computing power usually requires less energy than performing the same task over a longer period of time with less computing power.

Using the powersave profile can prolong battery life if a laptop is in an idle state, or performing only computationally undemanding operations. For such operations, higher latency in return for lower energy consumption is generally acceptable, or the operations do not need to be finished quickly, for example using IRC, viewing simple web pages, or playing audio and video files.

For detailed information on Tuned and power-saving profiles provided with tuned-adm, see the Tuned chapter in the Red Hat Enterprise Linux 7 Performance Tuning Guide.

The powertop2tuned utility allows you to create custom Tuned profiles from PowerTOP suggestions. For information on PowerTOP, see Section 2.2, “PowerTOP”.

To install the powertop2tuned utility, use:

~]# yum install tuned-utils

To create a custom profile, use:

~]# powertop2tuned new_profile_name

By default, powertop2tuned creates profiles in the /etc/tuned/ directory, and bases the custom profile on the currently selected Tuned profile. For safety reasons, all PowerTOP tunings are initially disabled in the new profile. To enable tunings, uncomment them in the /etc/tuned/profile_name/tuned.conf file.

You can use the --enable or -e option to generate a new profile that enables most of the tunings suggested by PowerTOP. Certain potentially problematic tunings, such as the USB autosuspend, are disabled by default and need to be uncommented manually.

By default, the new profile is not activated. To activate it, use:

~]# tuned-adm profile new_profile_name

For a complete list of options that powertop2tuned supports, use:

~]$ powertop2tuned --help