cpupower 调整CPU主频

1、调节策略

performance：将CPU频率固定工作在其支持的最高运行频率上，不动态调节，可以获取到最大的性能。

powersave: 将 CPU 频率设置为最低的所谓 “省电” 模式，CPU 会固定工作在其支持的最低运行频率上。

因此这两种 governors 都属于静态 governor，即在使用它们时 CPU 的运行频率不会根据系统运行时负载的变化动态作出调整。

这两种 governors 对应的是两种极端的应用场景，使用 performance governor 是对系统高性能的最大追求，而使用 powersave governor 则是对系统低功耗的最大追求。

userspace：最早的 cpufreq 子系统通过 userspace governor 为用户提供了这种灵活性。

系统将变频策略的决策权交给了用户态应用程序，并提供了相应的接口供用户态应用程序调节 CPU 运行频率使用。

ondemand：按需快速动态调整 CPU 频率，一有 cpu 计算量的任务，就会立即达到最大频率运行，等执行完毕就立即回到最低频率；

ondemand：userspace 是内核态的检测，用户态调整，效率低。

conservative: 与 ondemand 不同，平滑地调整 CPU 频率，频率的升降是渐变式的, 会自动在频率上下限调整，和 ondemand 的区别在于它会按需分配频率，而不是一味追求最高频率；

2、查看当前cpu可用的策略

[root@CENTOS ~] cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors 
conservative userspace powersave ondemand performance

3、查看当前cpu生效的策略

[root@CENTOS ~] cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
conservative

4、查看当前CPU频率

[root@CENTOS ~] cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
1000000

5、查看当前所有CPU的信息

[root@CENTOS ~] cpupower -c all frequency-info
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: 1000 MHz - 1.90 GHz
  available frequency steps:  1.90 GHz, 1.90 GHz, 1.80 GHz, 1.70 GHz, 1.60 GHz, 1.50 GHz, 1.40 GHz, 1.30 GHz, 1.20 GHz, 1.10 GHz, 1000 MHz
  available cpufreq governors: conservative userspace powersave ondemand performance
  current policy: frequency should be within 1000 MHz and 1.90 GHz.
                  The governor "conservative" may decide which speed to use
                  within this range.
  current CPU frequency: 1000 MHz (asserted by call to hardware)
  boost state support:
    Supported: yes
    Active: yes

6、设置所有CPU的模式

#设置所有CPU为性能模式
[root@CENTOS57 ~] cpupower -c all frequency-set -g performance
Setting cpu: 0
Setting cpu: 1
Setting cpu: 2
Setting cpu: 3
Setting cpu: 4
Setting cpu: 5
Setting cpu: 6
Setting cpu: 7
Setting cpu: 8
Setting cpu: 9
Setting cpu: 10
Setting cpu: 11
Setting cpu: 12
Setting cpu: 13
Setting cpu: 14
Setting cpu: 15

cpupower -c all frequency-set -g powersave
cpupower -c all frequency-set -g "conservative"

7、查看某个CPU的信息

[root@CENTOS57 ~] cpupower -c 1 frequency-info
analyzing CPU 1:
  driver: acpi-cpufreq
  CPUs which run at the same hardware frequency: 1
  CPUs which need to have their frequency coordinated by software: 1
  maximum transition latency: 10.0 us
  hardware limits: 1000 MHz - 1.90 GHz
  available frequency steps:  1.90 GHz, 1.90 GHz, 1.80 GHz, 1.70 GHz, 1.60 GHz, 1.50 GHz, 1.40 GHz, 1.30 GHz, 1.20 GHz, 1.10 GHz, 1000 MHz
  available cpufreq governors: conservative userspace powersave ondemand performance
  current policy: frequency should be within 1000 MHz and 1.90 GHz.
                  The governor "performance" may decide which speed to use
                  within this range.
  current CPU frequency: 1.90 GHz (asserted by call to hardware)
  boost state support:
    Supported: yes
    Active: yes

cpupower -c 0 frequency-info        #查看CPU0的信息
cpupower -c 1 frequency-info        #查看CPU1的信息
cpupower -c 2 frequency-info        #查看CPU2的信息

8、查看CPU的频率

[root@CENTOS57 ~] cat /proc/cpuinfo | grep "cpu MHz*"
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000
cpu MHz         : 1901.000