RHEL/CentOS 在 6.3 版本以后引入了一套新的系統(tǒng)調(diào)優(yōu)工具 tuned/tuned-adm，其中 tuned 是服務(wù)端程序，用來監(jiān)控和收集系統(tǒng)各個(gè)組件的數(shù)據(jù)，并依據(jù)數(shù)據(jù)提供的信息動(dòng)態(tài)調(diào)整系統(tǒng)設(shè)置，達(dá)到動(dòng)態(tài)優(yōu)化系統(tǒng)的目的；tuned-adm 是客戶端程序，用來和 tuned 打交道，用命令行的方式管理和配置 tuned，tuned-adm 提供了一些預(yù)先配置的優(yōu)化方案可供直接使用，比如：筆記本、虛擬機(jī)、存儲(chǔ)服務(wù)器等。
如果你正在使用筆記本（電池電源），想優(yōu)化系統(tǒng)、節(jié)約電源又不想知道太多這方面的細(xì)節(jié)，就可以用 tuned/tuned-adm 這套工具并應(yīng)用 laptop-battery-powersave 方案來調(diào)整和優(yōu)化系統(tǒng)。當(dāng)然不同的系統(tǒng)和應(yīng)用場景有不同的優(yōu)化方案，tuned-adm 預(yù)先配置的優(yōu)化策略不是總能滿足要求，這時(shí)候就需要定制，tuned-adm 允許用戶自己創(chuàng)建和定制新的調(diào)優(yōu)方案。
安裝和啟動(dòng) tuned:
# yum update
# yum install tuned
# service tuned start
# chkconfig tuned on
# service ktune start
# chkconfig ktune on
查看當(dāng)前優(yōu)化方案：
# tuned-adm active
Current active profile: default
Service tuned: enabled, running
Service ktune: enabled, running
查看預(yù)先配置好的優(yōu)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
如果服務(wù)器是虛擬機(jī)母機(jī)的話，可以選用 virtual-host 方案優(yōu)化。如果報(bào)錯(cuò) “kernel.sched_migration_cost” is an unknown key 可以通過編輯 sysctl.ktune 這個(gè)文件解決。
# 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
如果是企業(yè)存儲(chǔ)服務(wù)器的話，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 ]
上面預(yù)定的方案不是總能滿足要求，如果有自己的需求可以定制自己的方案。自己定制很容易，切換到優(yōu)化方案的配置目錄，拷貝一個(gè)例子，然后編輯里面的相關(guān)參數(shù)就可以了，使用 tuned-adm list 命令會(huì)看到剛創(chuàng)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
