windows 如何禁用动态频率缩放？

How to Disable Dynamic Frequency Scaling?

提问by martinus

I would like to do some microbenchmarks, and try to do them right. Unfortunately dynamic frequency scaling makes benchmarking highly unreliable.

我想做一些微基准测试，并尝试正确地完成它们。不幸的是，动态频率缩放使基准测试非常不可靠。

Is there a way to programmatically (C++, Windows) find out if dynamic frequency scaling is enabled? If, can this be disabled in a program?

有没有办法以编程方式（C++、Windows）找出是否启用了动态频率缩放？如果，可以在程序中禁用它吗？

Ive tried to just use a warmup phase that uses 100% CPU for a second before the actual benchmark takes place, but this turned out to be not reliable either.

我曾尝试在实际基准测试发生之前使用 100% CPU 一秒钟的预热阶段，但结果证明这也不可靠。

UPDATE: Even when I disable SpeedStep in the BIOS, cpu-z shows that the frequency changes between 1995 and 2826 GHz

更新：即使我在 BIOS 中禁用 SpeedStep，cpu-z 也显示频率在 1995 和 2826 GHz 之间变化

回答by Vantomex

In general, you need to do the following steps:

一般来说，您需要执行以下步骤：

• Call CallNtPowerInformation()and pass SystemPowerCapabilitiesto InformationLevelparameter, set lpInputBufferand nInputBufferSizeto NULL, then set lpOutputBufferto SYSTEM_POWER_CAPABILITIESstructure, and set nOutputBufferSizeto the size of the structure. After this first call, SYSTEM_POWER_CAPABILITIESstructure containing the current system power capabilities. To check whether the system supports processor throttling, read the value of ProcessorThrottle.

• There are other two members we are interested in, they are, ProcessorMinThrottleand ProcessorMaxThrottle; they represents the minimum and maximum level of system processor throttling supported, expressed as a percentage. If both members has already values 100%, this means CPU throttling is currently disabled, so you don't need to reconfigure it.

• To disable CPU throttling, you need to set ProcessorMinThrottleand ProcessorMaxThrottleto 100%. To do this, call CallNtPowerInformation()again and pass SystemPowerCapabilitiesto InformationLevelparameter; but now, set lpInputBufferto the SYSTEM_POWER_CAPABILITIES structure in which the two members has been set to 100%. I'm sure you know what to do next.

• 呼叫CallNtPowerInformation()并传递SystemPowerCapabilities到InformationLevel参数，设定lpInputBuffer和nInputBufferSize到NULL，则设置lpOutputBuffer到SYSTEM_POWER_CAPABILITIES结构，并设置nOutputBufferSize到所述结构的尺寸。在第一次调用之后，SYSTEM_POWER_CAPABILITIES包含当前系统电源功能的结构。要检查系统是否支持处理器节流，请读取ProcessorThrottle的值。

• 我们还对另外两个成员感兴趣，它们是ProcessorMinThrottle和ProcessorMaxThrottle；它们表示支持的系统处理器节流的最小和最大级别，以百分比表示。如果两个成员的值都为 100%，这意味着 CPU 节流当前已禁用，因此您无需重新配置它。

• 要禁用 CPU 节流，您需要将ProcessorMinThrottle和ProcessorMaxThrottle设置为100%。为此，CallNtPowerInformation()再次调用并将SystemPowerCapabilities传递给InformationLevel参数；但是现在，将lpInputBuffer设置为SYSTEM_POWER_CAPABILITIES结构，其中两个成员已设置为100%。我相信你知道下一步该怎么做。

In non-programmatic way, you can also get/set Windows Power Optionsusing the Windows built-in command-line tools, that is, PowerCfg.

通过非编程方式，您还可以使用 Windows 内置命令行工具（即PowerCfg ）获取/设置 Windows电源选项。

Further Reading

进一步阅读

• Power Management
• Power Management Functions

• 能源管理
• 电源管理功能

回答by Sebastian Graf

So far, none of the above CallNtPowerInformationoptions worked for me. The relevant ProcessorThrottlefield of SYSTEM_POWER_CAPABILITIESwas FALSEand changing some SYSTEM_POWER_POLICYs didn't work.

到目前为止，上述CallNtPowerInformation选项都不适合我。的相关ProcessorThrottle领域SYSTEM_POWER_CAPABILITIES是FALSE，改变一些SYSTEM_POWER_POLICYs 不起作用。

However, https://www.geeks3d.com/20170213/how-to-disable-intel-turbo-boost-technology-on-a-notebook/#_24outlines a way to make an option available in the power management settings.

但是，https://www.geeks3d.com/20170213/how-to-disable-intel-turbo-boost-technology-on-a-notebook/#_24 概述了一种在电源管理设置中提供选项的方法。

With ProcMon, I was able to trace it back to the following registry manipulations:

使用 ProcMon，我能够将其追溯到以下注册表操作：

1. Read the ActivePowerSchemeSZvalue under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\User\PowerSchemesto get the active power plan
2. Set the ACSettingIndexand/or DCSettingIndexDWORDunder Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\User\PowerSchemes\<above active power plan GUID>\54533251-82be-4824-96c1-47b60b740d00\be337238-0d82-4146-a960-4f3749d470c7to 0 (Disabled, or whatever you choose) from 2 (High)

1. 读取下面的ActivePowerSchemeSZ值HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\User\PowerSchemes以获取活动电源计划
2. 将ACSettingIndex和/或DCSettingIndexDWORD低于Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Power\User\PowerSchemes\<above active power plan GUID>\54533251-82be-4824-96c1-47b60b740d00\be337238-0d82-4146-a960-4f3749d470c72（高）设置为 0（禁用，或您选择的任何内容）

Unfortunately, the relevant keys are owned by the system, which either means you have to prompt the user (which has to have admin access) to change the permissions of the key or you have to use powercfgto manipulate the setting. The latter is preferrable and actually seems to work, even without admin access (courtesy of https://docs.microsoft.com/en-us/windows-server/administration/performance-tuning/hardware/power/power-performance-tuning#processor-performance-boost-mode):

不幸的是，相关密钥归系统所有，这意味着您必须提示用户（必须具有管理员访问权限）更改密钥的权限，或者您必须使用它powercfg来操作设置。后者更可取，实际上似乎也能工作，即使没有管理员访问权限（由https://docs.microsoft.com/en-us/windows-server/administration/performance-tuning/hardware/power/power-performance-tuning 提供） #processor-performance-boost-mode):

powercfg -setacvalueindex scheme_current sub_processor PERFBOOSTMODE 0
powercfg -setdcvalueindex scheme_current sub_processor PERFBOOSTMODE 0
powercfg -setactive scheme_current

回答by VladV

In Windows XP and later CPU speed is managed by power policy. Doesn't it turn off the scaling if you set "Max performance" mode in Windows power management dialog?

在 Windows XP 和更高版本中，CPU 速度由电源策略管理。如果在 Windows 电源管理对话框中设置“最大性能”模式，它不会关闭缩放吗？

There're also some third party tools - SpeedSwitchXPfor example.

还有一些第三方工具 -例如SpeedSwitchXP。

Programmatically this could be done, I suppose, using CallNtPowerInformationfunction.

我想这可以通过编程方式完成，使用CallNtPowerInformation函数。