Unable to get current CPU frequency in Powershell or Python - windows

Question

I am trying to somehow programamtically log the CPU frequency of my windows 10 machine. However I apparently fail to get the current frequency as shown in the task manager.
in Powershell, using
get-wmiobject Win32_Processor -Property CurrentClockSpeed
does only return a clock speed that is exactly the maximum one (even though i can see in task manager that it is not running that high)
I even tried this solution: https://www.remkoweijnen.nl/blog/2014/07/18/get-actual-cpu-clock-speed-powershell/ but it did not give me anything but a static value = max value.
Even python's psutil does only return a static value.
Does anybody know how to get around this and actually somehow log the CPU frequency each x seconds?
any help would be appreciated, thanks!

Answer 1

TLDR: To find the Current Processor Frequency, you have to use the % Processor Performance performance counter:
$MaxClockSpeed = (Get-CimInstance CIM_Processor).MaxClockSpeed
$ProcessorPerformance = (Get-Counter -Counter "\Processor Information(_Total)\% Processor Performance").CounterSamples.CookedValue
$CurrentClockSpeed = $MaxClockSpeed*($ProcessorPerformance/100)
Write-Host "Current Processor Speed: " -ForegroundColor Yellow -NoNewLine
Write-Host $CurrentClockSpeed
The more in depth explanation as to why does querying WMI Win32_Processor for CurrentClockSpeed seem to always return the maximum frequency rather than the actual "Current Clock Speed"? In fact, why do all of the dozens of WMI/CMI/Perfmon counters all seem to return the "wrong" frequency? If CPU-Z and Task Manager can get it, what do we have to do to get the "actual" frequency? To answer that, we need to understand what CurrentClockSpeed is actually returning.
From the WMI documentation for Win32_Processor CurrentClockSpeed:
Current speed of the processor, in MHz. This value comes from the
Current Speed member of the Processor Information structure in the
SMBIOS information.
Great! One would think that this simple query should get us the current frequency. This worked great a dozen years ago, but nowadays it doesn't; because it really only works for two very specific cases:
When you have a processor that only runs at its defined stock speed.
When a mobile processor is asked by Windows to run at a different speed (e.g. moving to battery mode).
At startup, Widows gets the processor information and gets the Current Clock Speed. Most people are running their processor at the recommended settings so Current Clock Speed == Max Clock Speed, which mean that the two numbers match all the time. When you change power states, Windows will change the frequency, and CurrentClockSpeed will be changed as well.
Now, what happened a dozen years ago to essentially make CurrentClockSpeed completely inaccurate/irrelevant? You can ultimately thank Intel. They essentially blew this whole ideal value out of the water thanks to a new technology called Turbo Boost.
What does Turbo Boost have to do with this?
Turbo Boost dynamically changes the processor frequency based on the current load on the processor within the confines of voltage, current, and thermal envelopes. Almost all modern processors also now have power saving modes and can dynamically change their frequencies based on their current marketing buzzword (e.g. Turbo Boost (up), Cool'N'Quiet (down)).
The key point is: all this frequency moving up/down/off/on is all automatically done without Windows knowing about it. Because Windows doesn't know about it, the CurrentClockSpeed value could be completely inaccurate most of the time. In fact, Microsoft knows this, and when you open your Performance Monitor, and you look at the description under Processor Performance/Processor Frequency:
Processor Frequency is the frequency of the current processor in
megahertz. Some processors are capable of regulating their frequency
outside of the control of Windows. Processor Frequency will not
accurately reflect actual processor frequency on these systems. Use
Processor Information\% Processor Performance instead.
Fortunately this description gives us a hint of what we have to use to get the actual value: Processor Information\% Processor Performance
We can use Get-Counter to access the current Processor performance like so:
PS C:\> Get-Counter -Counter "\Processor Information(_Total)\% Processor Performance"
Timestamp CounterSamples
--------- --------------
2020-01-01 1:23:45 AM \\HAL9256\processor information(_total)\% processor performance :
153.697654229441
Here, you can see that my processor is running at 153% performance a.k.a. 153% of the frequency of the processor (yay for Turbo Boost!). We then query the MaxClockSpeed from CIM_Processor class (you can use WMI_Processor as well):
PS C:\> (Get-CimInstance CIM_Processor).MaxClockSpeed
2592
In order to calculate out the actual clock speed:
$MaxClockSpeed = (Get-CimInstance CIM_Processor).MaxClockSpeed
$ProcessorPerformance = (Get-Counter -Counter "\Processor Information(_Total)\% Processor Performance").CounterSamples.CookedValue
$CurrentClockSpeed = $MaxClockSpeed*($ProcessorPerformance/100)
Write-Host "Current Processor Speed: " -ForegroundColor Yellow -NoNewLine
Write-Host $CurrentClockSpeed
Then wrapping it up in a loop if you need it to run every 2 seconds (Ctrl+C to stop):
$MaxClockSpeed = (Get-CimInstance CIM_Processor).MaxClockSpeed
While($true){
$ProcessorPerformance = (Get-Counter -Counter "\Processor Information(_Total)\% Processor Performance").CounterSamples.CookedValue
$CurrentClockSpeed = $MaxClockSpeed*($ProcessorPerformance/100)
Write-Host "Current Processor Speed: " -ForegroundColor Yellow -NoNewLine
Write-Host $CurrentClockSpeed
Sleep -Seconds 2
}

Answer 2

With help of the PS code above and the doc of win32pdh, I'm able to get it work in Python:
from win32pdh import PDH_FMT_DOUBLE
from win32pdh import OpenQuery, CloseQuery, AddCounter
from win32pdh import CollectQueryData, GetFormattedCounterValue
def get_freq():
ncores = 16
paths = []
counter_handles = []
query_handle = OpenQuery()
for i in range(ncores):
paths.append("\Processor Information(0,{:d})\% Processor Performance".format(i))
counter_handles.append(AddCounter(query_handle, paths[i]))
CollectQueryData(query_handle)
time.sleep(1)
CollectQueryData(query_handle)
freq = []
for i in range(ncores):
(counter_type, value) = GetFormattedCounterValue(counter_handles[i], PDH_FMT_DOUBLE)
freq.append(value*2.496/100)
# 2.496 is my base speed, I didn't spend time to automate this part
# print("{:.3f} Ghz".format(max(freq)))
CloseQuery(query_handle)
return "{:.3f} GHz".format(max(freq))