Master Linux System Tuning with tuned‑adm: Profiles, Commands & Customization

RHEL/CentOS introduced the tuned/tuned‑adm system tuning suite after version 6.3. tuned runs as a daemon that monitors component data and dynamically adjusts settings, while tuned‑adm is a command‑line client for managing profiles.

For laptop users on battery power, the laptop‑battery‑powersave profile can reduce power consumption without deep configuration. Different environments (virtual machines, storage servers, etc.) have pre‑defined profiles, but they may not meet all requirements, so custom profiles can be created.

Installation and startup:

# yum update
# yum install tuned

# service tuned start
# chkconfig tuned on

# service ktune start
# chkconfig ktune on

Check the active profile:

# tuned‑adm active
Current active profile: default
Service tuned: enabled, running
Service ktune: enabled, running

List available profiles:

# tuned‑adm list
Available profiles:
- laptop‑battery‑powersave
- virtual‑guest
- desktop‑powersave
- sap
- server‑powersave
- virtual‑host
- throughput‑performance
- enterprise‑storage
- laptop‑ac‑powersave
- latency‑performance
- spindown‑disk
- default
Current active profile: default

For a virtual‑host machine, apply the virtual‑host profile. If the error “kernel.sched_migration_cost is an unknown key” appears, edit /etc/ktune.d/sysctl.ktune to comment or adjust the key.

# tuned‑adm profile virtual-host
Reverting to saved sysctl settings:                        [  OK  ]
Calling '/etc/ktune.d/tunedadm.sh stop':                   [  OK  ]
Reverting to cfq elevator: sda sdb sdc sdd sde sdf sdg     [  OK  ]
Stopping tuned:                                            [  OK  ]
Switching to profile 'virtual-host'
Applying deadline elevator: sda sdb sdc sdd sde sdf sdg    [  OK  ]
Applying ktune sysctl settings:
/etc/ktune.d/tunedadm.conf:                                [FAILED]
  error: "kernel.sched_migration_cost" is an unknown key

Calling '/etc/ktune.d/tunedadm.sh start':                  [  OK  ]
Applying sysctl settings from /etc/sysctl.conf
Starting tuned:                                            [  OK  ]

# vi /etc/tune-profiles/virtual-host/sysctl.ktune
...
#kernel.sched_migration_cost = 5000000
...

# tuned‑adm profile virtual-host

For enterprise storage servers, the enterprise‑storage profile can be used:

# tuned‑adm profile enterprise-storage
Stopping tuned:                                            [  OK  ]
Switching to profile 'enterprise-storage'
Applying deadline elevator: dm-0 sda sdb sdc sdd           [  OK  ]
Applying ktune sysctl settings:
/etc/ktune.d/tunedadm.conf:                                [  OK  ]
Calling '/etc/ktune.d/tunedadm.sh start':                  [  OK  ]
Applying sysctl settings from /etc/sysctl.conf
Starting tuned:                                            [  OK  ]

To create a custom profile, copy an existing one (e.g., virtual‑host) to a new directory, edit the parameters, and the new profile (e.g., my‑virtual‑host) will appear in the tuned‑adm list output.

# cd /etc/tune-profiles/
# cp -r virtual-host my-virtual-host
# vi my-virtual-host/*

# tuned‑adm list
Available profiles:
...
- my-virtual-host
Current active profile: virtual-host