Window用多了,会对操作系统的一些基础知识有所淡忘.比如这期说的CPU Governor和CPU Frequency.最近误打误撞发现linux下需要对cpu做一些特殊的设置,才能使得cpu发挥最大的效能.
先介绍一个工具–CPUPower, CPUPower是linux下展示和设置cpu相关属性的工具.
实验机器 ¶
cpu: i5-480m 笔记本: thinkpad x201 nn5, 2011年款
应用cpupower ¶
cpupower frequency-info
会看到如下的提示:
analyzing CPU 0: driver: acpi-cpufreq
CPUs which run at the same hardware frequency: 0
CPUs which need to have their frequency coordinated by software: 0
maximum transition latency: 10.0 us.
hardware limits: 1.20 GHz - 2.67 GHz
available frequency steps: 2.67 GHz, 2.67 GHz, 2.53 GHz, 2.40 GHz, 2.27 GHz, 2.13 GHz, 2.00 GHz, 1.87 GHz, 1.73 GHz, 1.60 GHz, 1.47 GHz, 1.33 GHz, 1.20 GHz
available cpufreq governors: userspace, ondemand, performance
current policy: frequency should be within 1.20 GHz and 2.67 GHz.
The governor “performance” may decide which speed to use
within this range.
current CPU frequency is 2.67 GHz (asserted by call to hardware).
boost state support:
Supported: yes
Active: yes
2200 MHz max turbo 2 active cores
2200 MHz max turbo 1 active cores
从上面的输出结果可以看出cpu使用的Governor是performance, 当前cpu频率是2.67GHz. CPU可用的Governor有userspace, ondemand, performance, cpu可用的频率有2.67 GHz, 2.67 GHz, 2.53 GHz, 2.40 GHz, 2.27 GHz, 2.13 GHz, 2.00 GHz, 1.87 GHz, 1.73 GHz, 1.60 GHz, 1.47 GHz, 1.33 GHz, 1.20 GHz.
CPU Governor ¶
设置Governor ¶
cpupower -c all frequency-set --governor performance
使用如上命令设置cpu governor为performance
设置频率 ¶
cpupower -c all frequency-set -f 1.33GHz
使用如上命令设置cpu的频率为1.33GHz
其他 ¶
使用过程中可能会遇到一个问题,当笔记本电脑没有接电池只接AC的时候,linux默认会使用最低频率.如想突破此限制,可以在内核启动参数中添加如下参数:
processor.ignore_ppc=1
此参数会忽略bios的限制.