每次从睡眠中恢复后，CPU时钟变慢

我在Lenovo Y50-70上运行kubuntu 15.10，我的CPU时钟有一个非常烦人的问题：每当计算机从睡眠状态恢复时，CPU时钟的最大值就会降低，这不仅会发生一次，而且会在每次恢复的时钟都比较慢，直到从最初的3.6 GHz降低到〜600 MHz。

alain@alain-Y50-70:~$ sudo -i
[sudo] password for alain: 
root@alain-Y50-70:~# cpupower frequency-info
analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 3.60 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 800 MHz and 3.60 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 817 MHz (asserted by call to hardware).
  boost state support:
    Supported: yes
    Active: yes
root@alain-Y50-70:~# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
100
root@alain-Y50-70:~# cpupower frequency-info
analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 3.60 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 800 MHz and 2.88 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 800 MHz (asserted by call to hardware).
  boost state support:
    Supported: yes
    Active: yes
root@alain-Y50-70:~# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
80
root@alain-Y50-70:~# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
60
root@alain-Y50-70:~# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
40
root@alain-Y50-70:~# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct                                 
40                                                                                                         
root@alain-Y50-70:~# cpupower frequency-info                                 
analyzing CPU 0:                                                                                           
  driver: intel_pstate                                                                                     
  CPUs which run at the same hardware frequency: 0                                                         
  CPUs which need to have their frequency coordinated by software: 0                                       
  maximum transition latency: 0.97 ms.                                                                     
  hardware limits: 800 MHz - 3.60 GHz                                                                      
  available cpufreq governors: performance, powersave                                                      
  current policy: frequency should be within 800 MHz and 1.44 GHz.                                         
                  The governor "powersave" may decide which speed to use                                   
                  within this range.                                                                       
  current CPU frequency is 699 MHz (asserted by call to hardware).                                         
  boost state support:                                                                                     
    Supported: yes                                                                                         
    Active: yes                                                                                            
root@alain-Y50-70:~# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct                                 
40                                                                                                         
root@alain-Y50-70:~# cpupower frequency-info                                 
analyzing CPU 0:                                                                                           
  driver: intel_pstate                                                                                     
  CPUs which run at the same hardware frequency: 0                                                         
  CPUs which need to have their frequency coordinated by software: 0                                       
  maximum transition latency: 0.97 ms.                                                                     
  hardware limits: 800 MHz - 3.60 GHz                                                                      
  available cpufreq governors: performance, powersave                                                      
  current policy: frequency should be within 800 MHz and 1.44 GHz.                                         
                  The governor "powersave" may decide which speed to use                                   
                  within this range.                                                                       
  current CPU frequency is 605 MHz (asserted by call to hardware).                                         
  boost state support:                                                                                     
    Supported: yes                                                                                         
    Active: yes                                                                                            
root@alain-Y50-70:~#                                                                                       

我在上面的命令之间使计算机处于睡眠状态。如您所见，首先max_perf_pct逐步降低，直到达到40，然后保持40，但时钟速度继续降低。笔记本计算机是否已插入以及温度是否正常都没关系。

我认为它可能与此错误有关：https : //bugzilla.kernel.org/show_bug.cgi?id=90421

最大的问题是我找不到手动将最大时钟设置回3.6 GHz的方法。首先我尝试了cpupower frequency-set -u 3.60GHz：

root@alain-Y50-70:~# cpupower frequency-set -u 3.60GHz
Setting cpu: 0
Setting cpu: 1
Setting cpu: 2
Setting cpu: 3
Setting cpu: 4
Setting cpu: 5
Setting cpu: 6
Setting cpu: 7
root@alain-Y50-70:~# cpupower frequency-info
analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 3.60 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 800 MHz and 1.44 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 699 MHz (asserted by call to hardware).
  boost state support:
    Supported: yes
    Active: yes
root@alain-Y50-70:~# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
40

但这似乎是错误的方法，因为使用了Intel P-State驱动程序，因此我尝试echo 100 >/sys/devices/system/cpu/intel_pstate/max_perf_pct了无效：

root@alain-Y50-70:~# echo 100 >/sys/devices/system/cpu/intel_pstate/max_perf_pct
root@alain-Y50-70:~# cpupower frequency-info
analyzing CPU 0:
  driver: intel_pstate
  CPUs which run at the same hardware frequency: 0
  CPUs which need to have their frequency coordinated by software: 0
  maximum transition latency: 0.97 ms.
  hardware limits: 800 MHz - 3.60 GHz
  available cpufreq governors: performance, powersave
  current policy: frequency should be within 800 MHz and 1.44 GHz.
                  The governor "powersave" may decide which speed to use
                  within this range.
  current CPU frequency is 700 MHz (asserted by call to hardware).
  boost state support:
    Supported: yes
    Active: yes
root@alain-Y50-70:~# cat /sys/devices/system/cpu/intel_pstate/max_perf_pct
40

我也曾尝试过performance州长，但没有成功。

如何将最大时钟频率设置回3.6 GHz？

您遇到的问题已被多次报告。
请参考此bugzilla错误报告。

该问题已经隔离到内核树中的特定提交。该提交还被反向移植到某些以前的稳定内核版本。
但是，实际的根本原因是Lenovo BIOS问题。从linux-pm电子邮件线程引用：

BIOS报告虚假的被动跳变点值，即0摄氏度...。要解决此虚假的BIOS，我们应通过检查跳变点值来禁用那些无效的跳变点，

如果返回一个或两个版本，则Lenovo将正常工作（已知4.2.0-19可以正常工作）。

您的问题与时钟调制（寄存器0x19A）无关，除非您的电池电量低于30％（未经证实，但值得怀疑）。

参考：
http :
//ubuntuforums.org/showthread.php?t=2316101奇怪的cpufreq缩放问题：无论调节器如何，
当电池电量不足30％时，i3在500Mhz时，最大cpufreq都会逐渐下降，http ：//marc.info/
？ t = 145816738700001＆r = 1＆w = 2