This documentation explains how to use the TuneD application to monitor and optimize the throughput, latency, and power consumption of your system in different scenarios.

Getting started with TuneD

As a system administrator, you can use the TuneD application to optimize the performance profile of your system for a variety of use cases.

The purpose of TuneD

TuneD is a service that monitors your system and optimizes the performance under certain workloads. The core of TuneD are profiles, which tune your system for different use cases.

TuneD is distributed with a number of predefined profiles for use cases such as:

  • High throughput

  • Low latency

  • Saving power

It is possible to modify the rules defined for each profile and customize how to tune a particular device. When you switch to another profile or deactivate TuneD, all changes made to the system settings by the previous profile revert back to their original state.

You can also configure TuneD to react to changes in device usage and adjusts settings to improve performance of active devices and reduce power consumption of inactive devices.

TuneD profiles

A detailed analysis of a system can be very time-consuming. TuneD provides a number of predefined profiles for typical use cases. You can also create, modify, and delete profiles.

The profiles provided with TuneD are 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

Syntax of profile configuration

The tuned.conf file can contain one [main] section and other sections for configuring plug-in instances. However, all sections are optional.

Lines starting with the hash sign (#) are comments.

Additional resources

  • tuned.conf(5) man page.

The default TuneD profile

During the installation, the best profile for your system is selected automatically. Currently, the default profile is selected according to the following customizable rules:

Environment Default profile Goal

Compute nodes

throughput-performance

The best throughput performance

Virtual machines

virtual-guest

The best performance. If you are not interested in the best performance, you can change it to the balanced or powersave profile.

Other cases

balanced

Balanced performance and power consumption
Additional resources

  • tuned.conf(5) man page.

Merged TuneD profiles

As an experimental feature, it is possible to select more profiles at once. TuneD will try to merge them during the load.

If there are conflicts, the settings from the last specified profile takes precedence.

Example 1. Low power consumption in a virtual guest

The following example optimizes the system to run in a virtual machine for the best performance and concurrently tunes it for low power consumption, while the low power consumption is the priority:

# tuned-adm profile virtual-guest powersave
Warning
 Merging is done automatically without checking whether the resulting combination of parameters makes sense. Consequently, the feature might tune some parameters the opposite way, which might be counterproductive: for example, setting the disk for high throughput by using the throughput-performance profile and concurrently setting the disk spindown to the low value by the spindown-disk profile.
Additional resources

  • tuned.conf(5) man page.

The location of TuneD profiles

TuneD stores profiles in the following directories:

/usr/lib/tuned/

Distribution-specific profiles are stored in the directory. Each profile has its own directory. The profile consists of the main configuration file called tuned.conf, and optionally other files, for example helper scripts.

/etc/tuned/

If you need to customize a profile, copy the profile directory into the directory, which is used for custom profiles. If there are two profiles of the same name, the custom profile located in /etc/tuned/ is used.

Additional resources

  • tuned.conf(5) man page.

TuneD profiles distributed with RHEL

The following is a list of profiles that are installed with TuneD on Red Hat Enterprise Linux.

Note
 There might be more product-specific or third-party TuneD profiles available. Such profiles are usually provided by separate RPM packages.
balanced

The default power-saving profile. It is intended to be a compromise between performance and power consumption. It uses auto-scaling and auto-tuning whenever possible. The only drawback is the increased latency. In the current TuneD release, it enables the CPU, disk, audio, and video plugins, and activates the conservative CPU governor. The radeon_powersave option uses the dpm-balanced value if it is supported, otherwise it is set to auto.

It changes the energy_performance_preference attribute to the normal energy setting. It also changes the scaling_governor policy attribute to either the conservative or powersave CPU governor.

powersave

A profile for maximum power saving performance. It can throttle the performance in order to minimize the actual power consumption. In the current TuneD release it enables USB autosuspend, WiFi power saving, and Aggressive Link Power Management (ALPM) power savings for SATA host adapters. It also schedules multi-core power savings for systems with a low wakeup rate and activates the ondemand governor. It enables AC97 audio power saving or, depending on your system, HDA-Intel power savings with a 10 seconds timeout. If your system contains a supported Radeon graphics card with enabled KMS, the profile configures it to automatic power saving. On ASUS Eee PCs, a dynamic Super Hybrid Engine is enabled.

It changes the energy_performance_preference attribute to the powersave or power energy setting. It also changes the scaling_governor policy attribute to either the ondemand or powersave CPU governor.

Note

In certain cases, the balanced profile is more efficient compared to the powersave profile.

Consider there is a defined amount of work that needs to be done, for example a video file that needs to be transcoded. Your machine might consume less energy if the transcoding is done on the full power, because the task is finished quickly, the machine starts to idle, and it can automatically step-down to very efficient power save modes. On the other hand, if you transcode the file with a throttled machine, the machine consumes less power during the transcoding, but the process takes longer and the overall consumed energy can be higher.

That is why the balanced profile can be generally a better option.
throughput-performance

A server profile optimized for high throughput. It disables power savings mechanisms and enables sysctl settings that improve the throughput performance of the disk and network IO. CPU governor is set to performance.

It changes the energy_performance_preference and scaling_governor attribute to the performance profile.

accelerator-performance

The accelerator-performance profile contains the same tuning as the throughput-performance profile. Additionally, it locks the CPU to low C states so that the latency is less than 100us. This improves the performance of certain accelerators, such as GPUs.

latency-performance

A server profile optimized for low latency. It disables power savings mechanisms and enables sysctl settings that improve latency. CPU governor is set to performance and the CPU is locked to the low C states (by PM QoS).

It changes the energy_performance_preference and scaling_governor attribute to the performance profile.

network-latency

A profile for low latency network tuning. It is based on the latency-performance profile. It additionally disables transparent huge pages and NUMA balancing, and tunes several other network-related sysctl parameters.

It inherits the latency-performance profile which changes the energy_performance_preference and scaling_governor attribute to the performance profile.

hpc-compute

A profile optimized for high-performance computing. It is based on the latency-performance profile.

network-throughput

A profile for throughput network tuning. It is based on the throughput-performance profile. It additionally increases kernel network buffers.

It inherits either the latency-performance or throughput-performance profile, and changes the energy_performance_preference and scaling_governor attribute to the performance profile.

virtual-guest

A profile designed for virtual guests based on the throughput-performance profile that, among other tasks, decreases virtual memory swappiness and increases disk readahead values. It does not disable disk barriers.

It inherits the throughput-performance profile and changes the energy_performance_preference and scaling_governor attribute to the performance profile.

virtual-host

A profile designed for virtual hosts based on the throughput-performance profile that, among other tasks, decreases virtual memory swappiness, increases disk readahead values, and enables a more aggressive value of dirty pages writeback.

It inherits the throughput-performance profile and changes the energy_performance_preference and scaling_governor attribute to the performance profile.

oracle

A profile optimized for Oracle databases loads based on throughput-performance profile. It additionally disables transparent huge pages and modifies other performance-related kernel parameters. This profile is provided by the tuned-profiles-oracle package.

desktop

A profile optimized for desktops, based on the balanced profile. It additionally enables scheduler autogroups for better response of interactive applications.

cpu-partitioning

The cpu-partitioning profile partitions the system CPUs into isolated and housekeeping CPUs. To reduce jitter and interruptions on an isolated CPU, the profile clears the isolated CPU from user-space processes, movable kernel threads, interrupt handlers, and kernel timers.

A housekeeping CPU can run all services, shell processes, and kernel threads.

You can configure the cpu-partitioning profile in /etc/tuned/cpu-partitioning-variables.conf file. The configuration options are:

isolated_cores=cpu-list

Lists CPUs to isolate. The list of isolated CPUs is comma-separated or the user can specify the range. You can specify a range using a dash, such as 3-5. This option is mandatory. Any CPU missing from this list is automatically considered a housekeeping CPU.

no_balance_cores=cpu-list

Lists CPUs which are not considered by the kernel during system wide process load-balancing. This option is optional. This is usually the same list as isolated_cores.

For more information on cpu-partitioning, see the tuned-profiles-cpu-partitioning(7) man page.

optimize-serial-console

A profile that tunes down I/O activity to the serial console by reducing the printk value. This should make the serial console more responsive. This profile is intended to be used as an overlay on other profiles. For example:

# tuned-adm profile throughput-performance optimize-serial-console
mssql

A profile provided for Microsoft SQL Server. It is based on the thoguhput-performance profile.

postgresql

A profile optimized for PostgreSQL databases loads based on throughput-performance profile. It additionally disables transparent huge pages and modifies other performance-related kernel parameters. This profile is provided by the tuned-profiles-postgresql package.

intel-sst

A profile optimized for systems with user-defined Intel Speed Select Technology configurations. This profile is intended to be used as an overlay on other profiles. For example:

# tuned-adm profile cpu-partitioning intel-sst

Real-time TuneD profiles distributed with RHEL

Real-time profiles are intended for systems running the real-time kernel. Without a special kernel build, they do not configure the system to be real-time. On RHEL, the profiles are available from additional repositories.

The following real-time profiles are available:

realtime

Use on bare-metal real-time systems.

Provided by the tuned-profiles-realtime package, which is available from the RT or NFV repositories.

realtime-virtual-host

Use in a virtualization host configured for real-time.

Provided by the tuned-profiles-nfv-host package, which is available from the NFV repository.

realtime-virtual-guest

Use in a virtualization guest configured for real-time.

Provided by the tuned-profiles-nfv-guest package, which is available from the NFV repository.

Static and dynamic tuning in TuneD

This section explains the difference between the two categories of system tuning that TuneD applies: static and dynamic.

Static tuning

Mainly consists of the application of predefined sysctl and sysfs settings and one-shot activation of several configuration tools such as ethtool.

Dynamic tuning

Watches how various system components are used throughout the uptime of your system. TuneD adjusts system settings dynamically based on that monitoring information.

For example, the hard drive is used heavily during startup and login, but is barely used later when the user might mainly work with applications such as web browsers or email clients. Similarly, the CPU and network devices are used differently at different times. TuneD monitors the activity of these components and reacts to the changes in their use.

By default, dynamic tuning is disabled. To enable it, edit the /etc/tuned/tuned-main.conf file and change the dynamic_tuning option to 1. TuneD then periodically analyzes system statistics and uses them to update your system tuning settings. To configure the time interval in seconds between these updates, use the update_interval option.

Currently implemented dynamic tuning algorithms try to balance the performance and powersave, and are therefore disabled in the performance profiles. Dynamic tuning for individual plug-ins can be enabled or disabled in the TuneD profiles.

Example 2. Static and dynamic tuning on a workstation

On a typical office workstation, the Ethernet network interface is inactive most of the time. Only a few emails go in and out or some web pages might be loaded.

For those kinds of loads, the network interface does not have to run at full speed all the time, as it does by default. TuneD has a monitoring and tuning plug-in for network devices that can detect this low activity and then automatically lower the speed of that interface, typically resulting in a lower power usage.

If the activity on the interface increases for a longer period of time, for example because a DVD image is being downloaded or an email with a large attachment is opened, TuneD detects this and sets the interface speed to maximum to offer the best performance while the activity level is high.

This principle is used for other plug-ins for CPU and disks as well.

TuneD no-daemon mode

You can run TuneD in no-daemon mode, which does not require any resident memory. In this mode, TuneD applies the settings and exits.

By default, no-daemon mode is disabled because a lot of TuneD functionality is missing in this mode, including:

  • D-Bus support

  • Hot-plug support

  • Rollback support for settings

To enable no-daemon mode, include the following line in the /etc/tuned/tuned-main.conf file:

daemon = 0

Installing and enabling TuneD

This procedure installs and enables the TuneD application, installs TuneD profiles, and presets a default TuneD profile for your system.

Procedure

  1. Install the tuned package:

    # yum install tuned

  2. Enable and start the tuned service:

    # systemctl enable --now tuned

  3. Optionally, install TuneD profiles for real-time systems:

    # yum install tuned-profiles-realtime tuned-profiles-nfv

  4. Verify that a TuneD profile is active and applied:

    $ tuned-adm active

Current active profile: balanced
    $ tuned-adm verify

Verification succeeded, current system settings match the preset profile.
See TuneD log file ('/var/log/tuned/tuned.log') for details.

Listing available TuneD profiles

This procedure lists all TuneD profiles that are currently available on your system.

Procedure

  • To list all available TuneD profiles on your system, use:

    $ tuned-adm list

Available profiles:
- balanced               - General non-specialized tuned profile
- desktop                - Optimize for the desktop use-case
- latency-performance    - Optimize for deterministic performance at the cost of increased power consumption
- network-latency        - Optimize for deterministic performance at the cost of increased power consumption, focused on low latency network performance
- network-throughput     - Optimize for streaming network throughput, generally only necessary on older CPUs or 40G+ networks
- powersave              - Optimize for low power consumption
- throughput-performance - Broadly applicable tuning that provides excellent performance across a variety of common server workloads
- virtual-guest          - Optimize for running inside a virtual guest
- virtual-host           - Optimize for running KVM guests
Current active profile: balanced

  • To display only the currently active profile, use:

    $ tuned-adm active

Current active profile: balanced
Additional resources

  • The tuned-adm(8) man page.

Setting a TuneD profile

This procedure activates a selected TuneD profile on your system.

Prerequisites
Procedure

  1. Optionally, you can let TuneD recommend the most suitable profile for your system:

    # tuned-adm recommend

balanced

  2. Activate a profile:

    # tuned-adm profile selected-profile

    Alternatively, you can activate a combination of multiple profiles:

    # tuned-adm profile profile1 profile2
    Example 3. A virtual machine optimized for low power consumption

    The following example optimizes the system to run in a virtual machine with the best performance and concurrently tunes it for low power consumption, while the low power consumption is the priority:

    # tuned-adm profile virtual-guest powersave

  3. View the current active TuneD profile on your system:

    # tuned-adm active

Current active profile: selected-profile

  4. Reboot the system:

    # reboot
Verification steps

  • Verify that the TuneD profile is active and applied:

    $ tuned-adm verify

Verification succeeded, current system settings match the preset profile.
See TuneD log file ('/var/log/tuned/tuned.log') for details.
Additional resources

  • tuned-adm(8) man page

Disabling TuneD

This procedure disables TuneD and resets all affected system settings to their original state before TuneD modified them.

Procedure

  • To disable all tunings temporarily:

    # tuned-adm off

    The tunings are applied again after the tuned service restarts.

  • Alternatively, to stop and disable the tuned service permanently:

    # systemctl disable --now tuned
Additional resources

  • tuned-adm(8) man page

Customizing TuneD profiles

You can create or modify TuneD profiles to optimize system performance for your intended use case.

Prerequisites

TuneD profiles

A detailed analysis of a system can be very time-consuming. TuneD provides a number of predefined profiles for typical use cases. You can also create, modify, and delete profiles.

The profiles provided with TuneD are 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

Syntax of profile configuration

The tuned.conf file can contain one [main] section and other sections for configuring plug-in instances. However, all sections are optional.

Lines starting with the hash sign (#) are comments.

Additional resources

  • tuned.conf(5) man page.

The default TuneD profile

During the installation, the best profile for your system is selected automatically. Currently, the default profile is selected according to the following customizable rules:

Environment Default profile Goal

Compute nodes

throughput-performance

The best throughput performance

Virtual machines

virtual-guest

The best performance. If you are not interested in the best performance, you can change it to the balanced or powersave profile.

Other cases

balanced

Balanced performance and power consumption
Additional resources

  • tuned.conf(5) man page.

Merged TuneD profiles

As an experimental feature, it is possible to select more profiles at once. TuneD will try to merge them during the load.

If there are conflicts, the settings from the last specified profile takes precedence.

Example 4. Low power consumption in a virtual guest

The following example optimizes the system to run in a virtual machine for the best performance and concurrently tunes it for low power consumption, while the low power consumption is the priority:

# tuned-adm profile virtual-guest powersave
Warning
 Merging is done automatically without checking whether the resulting combination of parameters makes sense. Consequently, the feature might tune some parameters the opposite way, which might be counterproductive: for example, setting the disk for high throughput by using the throughput-performance profile and concurrently setting the disk spindown to the low value by the spindown-disk profile.
Additional resources

  • tuned.conf(5) man page.

The location of TuneD profiles

TuneD stores profiles in the following directories:

/usr/lib/tuned/

Distribution-specific profiles are stored in the directory. Each profile has its own directory. The profile consists of the main configuration file called tuned.conf, and optionally other files, for example helper scripts.

/etc/tuned/

If you need to customize a profile, copy the profile directory into the directory, which is used for custom profiles. If there are two profiles of the same name, the custom profile located in /etc/tuned/ is used.

Additional resources

  • tuned.conf(5) man page.

Inheritance between TuneD profiles

TuneD profiles can be based on other profiles and modify only certain aspects of their parent profile.

The [main] section of TuneD profiles recognizes the include option:

[main]
include=parent

All settings from the parent profile are loaded in this child profile. In the following sections, the child profile can override certain settings inherited from the parent profile or add new settings not present in the parent profile.

You can create your own child profile in the /etc/tuned/ directory based on a pre-installed profile in /usr/lib/tuned/ with only some parameters adjusted.

If the parent profile is updated, such as after a TuneD upgrade, the changes are reflected in the child profile.

Example 5. A power-saving profile based on balanced

The following is an example of a custom profile that extends the balanced profile and sets Aggressive Link Power Management (ALPM) for all devices to the maximum powersaving.

[main]
include=balanced

[scsi_host]
alpm=min_power
Additional resources

  • tuned.conf(5) man page

Static and dynamic tuning in TuneD

This section explains the difference between the two categories of system tuning that TuneD applies: static and dynamic.

Static tuning

Mainly consists of the application of predefined sysctl and sysfs settings and one-shot activation of several configuration tools such as ethtool.

Dynamic tuning

Watches how various system components are used throughout the uptime of your system. TuneD adjusts system settings dynamically based on that monitoring information.

For example, the hard drive is used heavily during startup and login, but is barely used later when the user might mainly work with applications such as web browsers or email clients. Similarly, the CPU and network devices are used differently at different times. TuneD monitors the activity of these components and reacts to the changes in their use.

By default, dynamic tuning is disabled. To enable it, edit the /etc/tuned/tuned-main.conf file and change the dynamic_tuning option to 1. TuneD then periodically analyzes system statistics and uses them to update your system tuning settings. To configure the time interval in seconds between these updates, use the update_interval option.

Currently implemented dynamic tuning algorithms try to balance the performance and powersave, and are therefore disabled in the performance profiles. Dynamic tuning for individual plug-ins can be enabled or disabled in the TuneD profiles.

Example 6. Static and dynamic tuning on a workstation

On a typical office workstation, the Ethernet network interface is inactive most of the time. Only a few emails go in and out or some web pages might be loaded.

For those kinds of loads, the network interface does not have to run at full speed all the time, as it does by default. TuneD has a monitoring and tuning plug-in for network devices that can detect this low activity and then automatically lower the speed of that interface, typically resulting in a lower power usage.

If the activity on the interface increases for a longer period of time, for example because a DVD image is being downloaded or an email with a large attachment is opened, TuneD detects this and sets the interface speed to maximum to offer the best performance while the activity level is high.

This principle is used for other plug-ins for CPU and disks as well.

TuneD plug-ins

Plug-ins are modules in TuneD profiles that TuneD uses to monitor or optimize different devices on the system.

TuneD uses two types of plug-ins:

Monitoring plug-ins

Monitoring plug-ins are used to get information from a running system. The output of the monitoring plug-ins can be used by tuning plug-ins for dynamic tuning.

Monitoring plug-ins are automatically instantiated whenever their metrics are needed by any of the enabled tuning plug-ins. If two tuning plug-ins require the same data, only one instance of the monitoring plug-in is created and the data is shared.

Tuning plug-ins

Each tuning plug-in tunes an individual subsystem and takes several parameters that are populated from the TuneD profiles. Each subsystem can have multiple devices, such as multiple CPUs or network cards, that are handled by individual instances of the tuning plug-ins. Specific settings for individual devices are also supported.

Syntax for plug-ins in TuneD profiles

Sections describing plug-in instances are formatted in the following way:

[NAME]
type=TYPE
devices=DEVICES
NAME

is the name of the plug-in instance as it is used in the logs. It can be an arbitrary string.

TYPE

is the type of the tuning plug-in.

DEVICES

is the list of devices that this plug-in instance handles.

The devices line can contain a list, a wildcard (*), and negation (!). If there is no devices line, all devices present or later attached on the system of the TYPE are handled by the plug-in instance. This is same as using the devices=* option.

Example 7. Matching block devices with a plug-in

The following example matches all block devices starting with sd, such as sda or sdb, and does not disable barriers on them:

[data_disk]
type=disk
devices=sd*
disable_barriers=false

The following example matches all block devices except sda1 and sda2:

[data_disk]
type=disk
devices=!sda1, !sda2
disable_barriers=false

If no instance of a plug-in is specified, the plug-in is not enabled.

If the plug-in supports more options, they can be also specified in the plug-in section. If the option is not specified and it was not previously specified in the included plug-in, the default value is used.

Short plug-in syntax

If you do not need custom names for the plug-in instance and there is only one definition of the instance in your configuration file, TuneD supports the following short syntax:

[TYPE]
devices=DEVICES

In this case, it is possible to omit the type line. The instance is then referred to with a name, same as the type. The previous example could be then rewritten into:

Example 8. Matching block devices using the short syntax
[disk]
devices=sdb*
disable_barriers=false

Conflicting plug-in definitions in a profile

If the same section is specified more than once using the include option, the settings are merged. If they cannot be merged due to a conflict, the last conflicting definition overrides the previous settings. If you do not know what was previously defined, you can use the replace Boolean option and set it to true. This causes all the previous definitions with the same name to be overwritten and the merge does not happen.

You can also disable the plug-in by specifying the enabled=false option. This has the same effect as if the instance was never defined. Disabling the plug-in is useful if you are redefining the previous definition from the include option and do not want the plug-in to be active in your custom profile.

NOTE

TuneD includes the ability to run any shell command as part of enabling or disabling a tuning profile. This enables you to extend TuneD profiles with functionality that has not been integrated into TuneD yet.

You can specify arbitrary shell commands using the script plug-in.

Additional resources

  • tuned.conf(5) man page

Available TuneD plug-ins

This section lists all monitoring and tuning plug-ins currently available in TuneD.

Monitoring plug-ins

Currently, the following monitoring plug-ins are implemented:

disk

Gets disk load (number of IO operations) per device and measurement interval.

net

Gets network load (number of transferred packets) per network card and measurement interval.

load

Gets CPU load per CPU and measurement interval.

Tuning plug-ins

Currently, the following tuning plug-ins are implemented. Only some of these plug-ins implement dynamic tuning. Options supported by plug-ins are also listed:

cpu

Sets the CPU governor to the value specified by the governor option and dynamically changes the Power Management Quality of Service (PM QoS) CPU Direct Memory Access (DMA) latency according to the CPU load.

If the CPU load is lower than the value specified by the load_threshold option, the latency is set to the value specified by the latency_high option, otherwise it is set to the value specified by latency_low.

You can also force the latency to a specific value and prevent it from dynamically changing further. To do so, set the force_latency option to the required latency value.

eeepc_she

Dynamically sets the front-side bus (FSB) speed according to the CPU load.

This feature can be found on some netbooks and is also known as the ASUS Super Hybrid Engine (SHE).

If the CPU load is lower or equal to the value specified by the load_threshold_powersave option, the plug-in sets the FSB speed to the value specified by the she_powersave option. If the CPU load is higher or equal to the value specified by the load_threshold_normal option, it sets the FSB speed to the value specified by the she_normal option.

Static tuning is not supported and the plug-in is transparently disabled if TuneD does not detect the hardware support for this feature.

net

Configures the Wake-on-LAN functionality to the values specified by the wake_on_lan option. It uses the same syntax as the ethtool utility. It also dynamically changes the interface speed according to the interface utilization.

sysctl

Sets various sysctl settings specified by the plug-in options.

The syntax is name=value, where name is the same as the name provided by the sysctl utility.

Use the sysctl plug-in if you need to change system settings that are not covered by other plug-ins available in TuneD. If the settings are covered by some specific plug-ins, prefer these plug-ins.

usb

Sets autosuspend timeout of USB devices to the value specified by the autosuspend parameter.

The value 0 means that autosuspend is disabled.

vm

Enables or disables transparent huge pages depending on the Boolean value of the transparent_hugepages option.

Valid values of the transparent_hugepages option are:

  • "always"

  • "never"

  • "madvise"

audio

Sets the autosuspend timeout for audio codecs to the value specified by the timeout option.

Currently, the snd_hda_intel and snd_ac97_codec codecs are supported. The value 0 means that the autosuspend is disabled. You can also enforce the controller reset by setting the Boolean option reset_controller to true.

disk

Sets the disk elevator to the value specified by the elevator option.

It also sets:

  • APM to the value specified by the apm option

  • Scheduler quantum to the value specified by the scheduler_quantum option

  • Disk spindown timeout to the value specified by the spindown option

  • Disk readahead to the value specified by the readahead parameter

  • The current disk readahead to a value multiplied by the constant specified by the readahead_multiply option

In addition, this plug-in dynamically changes the advanced power management and spindown timeout setting for the drive according to the current drive utilization. The dynamic tuning can be controlled by the Boolean option dynamic and is enabled by default.

scsi_host

Tunes options for SCSI hosts.

It sets Aggressive Link Power Management (ALPM) to the value specified by the alpm option.

mounts

Enables or disables barriers for mounts according to the Boolean value of the disable_barriers option.

scheduler

Allows tuning of scheduling priorities, processes/threads/IRQs affinities, and CPU cores isolation.

The scheduler plugin uses perf event loop to catch newly created processes. By default it listens to perf.RECORD_COMM and perf.RECORD_EXIT events. By setting perf_process_fork parameter to true, perf.RECORD_FORK events will be also listened to. In other words, child processes created by the fork() system call will be processed. Since child processes inherit CPU affinity from their parents, the scheduler plugin usually does not need to explicitly process these events. As processing perf events can pose a significant CPU overhead, the perf_process_fork parameter is set to false by default and child processes are not processed by the scheduler plugin.

For perf events mmapped buffer is used. Under heavy load the buffer may overflow. In such cases the scheduler plugin may start missing events and not process some newly created processes. Increasing the buffer size may help. The buffer size can be set with the perf_mmap_pages parameter. Value of this parameter has to be power of 2. If it is not the power of 2, the nearest bigger power of 2 value is calculated from it and this calculated value is used. If the perf_mmap_pages parameter is omitted, the default kernel value is used, which should be 128 for the recent kernels (tested on kernel-5.9.8).

The default_irq_smp_affinity parameter controls the values TuneD writes to /proc/irq/default_smp_affinity. The following values are supported:

calc

Content of /proc/irq/default_smp_affinity will be calculated from the isolated_cores parameter. Non-isolated cores are calculated as an inversion of the isolated_cores. Then the intersection of the non-isolated cores and the previous content of /proc/irq/default_smp_affinity is written to /proc/irq/default_smp_affinity. If the intersection is an empty set, then just the non-isolated cores are written to /proc/irq/default_smp_affinity. This behavior is the default if the parameter default_irq_smp_affinity is omitted.

ignore

TuneD will not touch /proc/irq/default_smp_affinity.

cpulist such as 1,3-4

The cpulist is unpacked and written directly to /proc/irq/default_smp_affinity.

script

Executes an external script or binary when the profile is loaded or unloaded. You can choose an arbitrary executable.

Important
 The script plug-in is provided mainly for compatibility with earlier releases. Prefer other TuneD plug-ins if they cover the required functionality.

TuneD calls the executable with one of the following arguments:

  • start when loading the profile

  • stop when unloading the profile

You need to correctly implement the stop action in your executable and revert all settings that you changed during the start action. Otherwise, the roll-back step after changing your TuneD profile will not work.

Bash scripts can import the /usr/lib/tuned/functions Bash library and use the functions defined there. Use these functions only for functionality that is not natively provided by TuneD. If a function name starts with an underscore, such as _wifi_set_power_level, consider the function private and do not use it in your scripts, because it might change in the future.

Specify the path to the executable using the script parameter in the plug-in configuration.

Example 9. Running a Bash script from a profile

To run a Bash script named script.sh that is located in the profile directory, use:

[script]
script=${i:PROFILE_DIR}/script.sh
sysfs

Sets various sysfs settings specified by the plug-in options.

The syntax is name=value, where name is the sysfs path to use.

Use this plugin in case you need to change some settings that are not covered by other plug-ins. Prefer specific plug-ins if they cover the required settings.

video

Sets various powersave levels on video cards. Currently, only the Radeon cards are supported.

The powersave level can be specified by using the radeon_powersave option. Supported values are:

  • default

  • auto

  • low

  • mid

  • high

  • dynpm

  • dpm-battery

  • dpm-balanced

  • dpm-perfomance

For details, see www.x.org. Note that this plug-in is experimental and the option might change in future releases.

bootloader

Adds options to the kernel command line. This plug-in supports only the GRUB 2 boot loader.

Customized non-standard location of the GRUB 2 configuration file can be specified by the grub2_cfg_file option.

The kernel options are added to the current GRUB configuration and its templates. The system needs to be rebooted for the kernel options to take effect.

Switching to another profile or manually stopping the tuned service removes the additional options. If you shut down or reboot the system, the kernel options persist in the grub.cfg file.

The kernel options can be specified by the following syntax:

cmdline=arg1 arg2 ... argN
Example 10. Modifying the kernel command line

For example, to add the quiet kernel option to a TuneD profile, include the following lines in the tuned.conf file:

[bootloader]
cmdline=quiet

The following is an example of a custom profile that adds the isolcpus=2 option to the kernel command line:

[bootloader]
cmdline=isolcpus=2
acpi

Configures the ACPI driver.

The only currently supported option is platform_profile, which sets the ACPI platform profile sysfs attribute, a generic power/performance preference API for other drivers. Multiple profiles can be specified, separated by |. The first available profile is selected.

Example 11. Selecting a platform profile
[acpi]
platform_profile=low-power|quiet

Using this option, TuneD will try to set the platform profile to low-power. If that fails (e.g, because the system does not support the profile), it will try to set it to quiet.

Variables in TuneD profiles

Variables expand at run time when a TuneD profile is activated.

Using TuneD variables reduces the amount of necessary typing in TuneD profiles.

There are no predefined variables in TuneD profiles. You can define your own variables by creating the [variables] section in a profile and using the following syntax:

[variables]

variable_name=value

To expand the value of a variable in a profile, use the following syntax:

${variable_name}
Example 12. Isolating CPU cores using variables

In the following example, the ${isolated_cores} variable expands to 1,2; hence the kernel boots with the isolcpus=1,2 option:

[variables]
isolated_cores=1,2

[bootloader]
cmdline=isolcpus=${isolated_cores}

The variables can be specified in a separate file. For example, you can add the following lines to tuned.conf:

[variables]
include=/etc/tuned/my-variables.conf

[bootloader]
cmdline=isolcpus=${isolated_cores}

If you add the isolated_cores=1,2 option to the /etc/tuned/my-variables.conf file, the kernel boots with the isolcpus=1,2 option.

Additional resources

  • tuned.conf(5) man page

Built-in functions in TuneD profiles

Built-in functions expand at run time when a TuneD profile is activated.

You can:

  • Use various built-in functions together with TuneD variables

  • Create custom functions in Python and add them to TuneD in the form of plug-ins

To call a function, use the following syntax:

${f:function_name:argument_1:argument_2}

To expand the directory path where the profile and the tuned.conf file are located, use the PROFILE_DIR function, which requires special syntax:

${i:PROFILE_DIR}
Example 13. Isolating CPU cores using variables and built-in functions

In the following example, the ${non_isolated_cores} variable expands to 0,3-5, and the cpulist_invert built-in function is called with the 0,3-5 argument:

[variables]
non_isolated_cores=0,3-5

[bootloader]
cmdline=isolcpus=${f:cpulist_invert:${non_isolated_cores}}

The cpulist_invert function inverts the list of CPUs. For a 6-CPU machine, the inversion is 1,2, and the kernel boots with the isolcpus=1,2 command-line option.

Additional resources

  • tuned.conf(5) man page

Built-in functions available in TuneD profiles

The following built-in functions are available in all TuneD profiles:

PROFILE_DIR

Returns the directory path where the profile and the tuned.conf file are located.

exec

Executes a process and returns its output.

assertion

Compares two arguments. If they do not match, the function logs text from the first argument and aborts profile loading.

assertion_non_equal

Compares two arguments. If they match, the function logs text from the first argument and aborts profile loading.

kb2s

Converts kilobytes to disk sectors.

s2kb

Converts disk sectors to kilobytes.

strip

Creates a string from all passed arguments and deletes both leading and trailing white space.

virt_check

Checks whether TuneD is running inside a virtual machine (VM) or on bare metal:

  • Inside a VM, the function returns the first argument.

  • On bare metal, the function returns the second argument, even in case of an error.

cpulist_invert

Inverts a list of CPUs to make its complement. For example, on a system with 4 CPUs, numbered from 0 to 3, the inversion of the list 0,2,3 is 1.

cpulist2hex

Converts a CPU list to a hexadecimal CPU mask.

cpulist2hex_invert

Converts a CPU list to a hexadecimal CPU mask and inverts it.

hex2cpulist

Converts a hexadecimal CPU mask to a CPU list.

cpulist_online

Checks whether the CPUs from the list are online. Returns the list containing only online CPUs.

cpulist_present

Checks whether the CPUs from the list are present. Returns the list containing only present CPUs.

cpulist_unpack

Unpacks a CPU list in the form of 1-3,4 to 1,2,3,4.

cpulist_pack

Packs a CPU list in the form of 1,2,3,5 to 1-3,5.

intel_recommended_pstate

Returns recommended intel_pstate CPUFreq driver mode based on processor generation.

Creating new TuneD profiles

This procedure creates a new TuneD profile with custom performance rules.

Prerequisites
Procedure

  1. In the /etc/tuned/ directory, create a new directory named the same as the profile that you want to create:

    # mkdir /etc/tuned/my-profile

  2. In the new directory, create a file named tuned.conf. Add a [main] section and plug-in definitions in it, according to your requirements.

    For example, see the configuration of the balanced profile:

    [main]
summary=General non-specialized TuneD profile

[cpu]
governor=conservative
energy_perf_bias=normal

[audio]
timeout=10

[video]
radeon_powersave=dpm-balanced, auto

[scsi_host]
alpm=medium_power

  3. To activate the profile, use:

    # tuned-adm profile my-profile

  4. Verify that the TuneD profile is active and the system settings are applied:

    $ tuned-adm active

Current active profile: my-profile
    $ tuned-adm verify

Verification succeeded, current system settings match the preset profile.
See TuneD log file ('/var/log/tuned/tuned.log') for details.
Additional resources

  • tuned.conf(5) man page

Modifying existing TuneD profiles

This procedure creates a modified child profile based on an existing TuneD profile.

Prerequisites
Procedure

  1. In the /etc/tuned/ directory, create a new directory named the same as the profile that you want to create:

    # mkdir /etc/tuned/modified-profile

  2. In the new directory, create a file named tuned.conf, and set the [main] section as follows:

    [main]
include=parent-profile

    Replace parent-profile with the name of the profile you are modifying.

  3. Include your profile modifications.

    Example 14. Lowering swappiness in the throughput-performance profile

    To use the settings from the throughput-performance profile and change the value of vm.swappiness to 5, instead of the default 10, use:

    [main]
include=throughput-performance

[sysctl]
vm.swappiness=5

  4. To activate the profile, use:

    # tuned-adm profile modified-profile

  5. Verify that the TuneD profile is active and the system settings are applied:

    $ tuned-adm active

Current active profile: my-profile
    $ tuned-adm verify

Verification succeeded, current system settings match the preset profile.
See TuneD log file ('/var/log/tuned/tuned.log') for details.
Additional resources

  • tuned.conf(5) man page

Setting the disk scheduler using TuneD

This procedure creates and enables a TuneD profile that sets a given disk scheduler for selected block devices. The setting persists across system reboots.

In the following commands and configuration, replace:

  • device with the name of the block device, for example sdf

  • selected-scheduler with the disk scheduler that you want to set for the device, for example bfq

Prerequisites
Procedure

  1. Optional: Select an existing TuneD profile on which your profile will be based. For a list of available profiles, see https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/8/html/monitoring_and_managing_system_status_and_performance/getting-started-with-tuned_monitoring-and-managing-system-status-and-performance#tuned-profiles-distributed-with-rhel_getting-started-with-tuned.

    To see which profile is currently active, use:

    $ tuned-adm active

  2. Create a new directory to hold your TuneD profile:

    # mkdir /etc/tuned/my-profile

  3. Find the system unique identifier of the selected block device:

    $ udevadm info --query=property --name=/dev/device | grep -E '(WWN|SERIAL)'

ID_WWN=0x5002538d00000000_
ID_SERIAL=Generic-_SD_MMC_20120501030900000-0:0
ID_SERIAL_SHORT=20120501030900000
    Note

    The command in the this example will return all values identified as a World Wide Name (WWN) or serial number associated with the specified block device. Although it is preferred to use a WWN, the WWN is not always available for a given device and any values returned by the example command are acceptable to use as the device system unique ID.

  4. Create the /etc/tuned/my-profile/tuned.conf configuration file. In the file, set the following options:

    1. Optional: Include an existing profile:

      [main]
include=existing-profile

    2. Set the selected disk scheduler for the device that matches the WWN identifier:

      [disk]
devices_udev_regex=IDNAME=device system unique id
elevator=selected-scheduler

      Here:

      • Replace IDNAME with the name of the identifier being used (for example, ID_WWN).

      • Replace device system unique id with the value of the chosen identifier (for example, 0x5002538d00000000).

        To match multiple devices in the devices_udev_regex option, enclose the identifiers in parentheses and separate them with vertical bars:

        devices_udev_regex=(ID_WWN=0x5002538d00000000)|(ID_WWN=0x1234567800000000)

  5. Enable your profile:

    # tuned-adm profile my-profile
Verification steps

  1. Verify that the TuneD profile is active and applied:

    $ tuned-adm active

Current active profile: my-profile
    $ tuned-adm verify

Verification succeeded, current system settings match the preset profile.
See TuneD log file ('/var/log/tuned/tuned.log') for details.
Additional resources