使用 tuned/tuned-adm 工具动态调优系统 
RHEL/CentOS 在 6.3 版本以后引入了一套新的系统调优工具 tuned/tuned-adm，其中 tuned 是服务端程序，用来监控和收集系统各个组件的数据，并依据数据提供的信息动态调整系统设置，达到动态优化系统的目的；tuned-adm 是客户端程序，用来和 tuned 打交道，用命令行的方式管理和配置 tuned，tuned-adm 提供了一些预先配置的优化方案可供直接使用，比如：笔记本、虚拟机、存储服务器等。
如果你正在使用笔记本（电池电源），想优化系统、节约电源又不想知道太多这方面的细节，就可以用 tuned/tuned-adm 这套工具并应用 laptop-battery-powersave 方案来调整和优化系统。当然不同的系统和应用场景有不同的优化方案，tuned-adm 预先配置的优化策略不是总能满足要求，这时候就需要定制，tuned-adm 允许用户自己创建和定制新的调优方案。
安装和启动 tuned:
# yum update
# yum install tuned
# service tuned start
# chkconfig tuned on
# service ktune start
# chkconfig ktune on
# yum install tuned
# service tuned start
# chkconfig tuned on
# service ktune start
# chkconfig ktune on
查看当前优化方案：
# tuned-adm active
Current active profile: default
Service tuned: enabled, running
Service ktune: enabled, running
查看预先配置好的优化方案：
# 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
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
如果服务器是虚拟机母机的话，可以选用 virtual-host 方案优化。如果报错 “kernel.sched_migration_cost” is an unknown key 可以通过编辑 sysctl.ktune 这个文件解决。
# 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
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
如果是企业存储服务器的话，可以用 enterprise-storage 方案：
# 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 ]
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 ]
上面预定的方案不是总能满足要求，如果有自己的需求可以定制自己的方案。自己定制很容易，切换到优化方案的配置目录，拷贝一个例子，然后编辑里面的相关参数就可以了，使用 tuned-adm list 命令会看到刚创建的新方案 my-virtual-host：
# cd /etc/tune-profiles/
# cp -r virtual-host my-virtual-host
# vi my-virtual-host/*
# 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
- my-virtual-host
Current active profile: virtual-host
# cp -r virtual-host my-virtual-host
# vi my-virtual-host/*
# 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
- my-virtual-host
Current active profile: virtual-host
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