Tuesday, September 1, 2015

Improve performance on virtualized RHEL 7 server using tuned

Tuned is a dynamic adaptive system tuning daemon that tunes system settings dynamically depending on usage. You can configure tuned in RHEL 6/7 systems (and CentOS, Oracle Linux etc) using tuned-adm witch is the commandline tool for switching between different tuning profiles.

You can install it using:

# yum install tuned

You can view the list of available profiles and the current active profile using:

$ tuned-adm list
Available profiles:
- balanced
- desktop
- latency-performance
- network-latency
- network-throughput
- powersave
- throughput-performance
- virtual-guest
- virtual-host
Current active profile: virtual-guest

For virtualized servers you can switch to virtual-guest profile using:

# tuned-adm profile virtual-guest
Switching to profile 'virtual-guest'
Applying deadline elevator: dm-0 dm-1 dm-2 sda sdb         [  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  ]

The following are the descriptions for virtual-guest and throughput-performance profile as in the man page.

virtual-guest
Profile optimized for virtual guests based on throughput-performance profile. It additionally decreases virtual memory swappiness and increases dirty_ratio settings.

throughput-performance
Profile for typical throughput performance tuning. Disables power saving mechanisms and enables sysctl settings that improve the throughput performance of your disk and network IO. CPU governor is set to performance and CPU energy performance bias is set to performance. Disk readahead values are increased.

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