[VB.NET] How many CPU cores?

[James Rose]

Hey gang,

Is there a way within VB.NET 2005 to detect how many cores the CPU has? and/or how many CPUs are on the system?

Thanks kindly

[azcodemonkey]

  jameswjrose said:

Hey gang,

Is there a way within VB.NET 2005 to detect how many cores the CPU has? and/or how many CPUs are on the system?

Thanks kindly

You'll probably have to utilize p/invoke to leverage the Win32 API. I'm fairly certain there's no native .NET way to do this.

[James Rose]

Thanks, at least I feel better on not finding it. Last I checked (a few years ago) there were no Windows APIs available to denote CPU info. Intel had a DLL we could use but...

Thanks.

[rnvrajagopal]

  jameswjrose said:

Thanks, at least I feel better on not finding it. Last I checked (a few years ago) there were no Windows APIs available to denote CPU info. Intel had a DLL we could use but...

Thanks.

System.Environment.ProcessorCount will get you that.

[James Rose]

  rnvrajagopal said:

System.Environment.ProcessorCount will get you that.

Great. Thanks kindly. Now I have to try this at home, where I have a dual core to see if it reports 1 or 2 (what is the API denoting as a CPU... a core or a chip... <shrug> But thank you very much!

[azcodemonkey]

That doesn't distinguish between CPUs and cores. AFAIK, you have to look at CPUID to determine if the reported CPUs are indeed cores on a chip or separate CPUs. With the ProcessorCount property, I'd hazard that it doesn't distinguish between cores or CPUs or HyperThreading.

[Malisk]

On Windows Vista and using the .NET WMI API, it should be possible to detect. (and thus in a .NET, non-P/Invoke way)

However, on XP and earlier, the WMI Win32_Processor objects didn't distinguish as well between logical (cores, HyperThreading...) and physical processors. Executing the WMI query "SELECT * FROM Win32_Processor" should return two items for a single dual core CPU on XP, but only one item in that case on Vista.

Here's the code that should work on Vista: (untested)

' Requires an import for System.Management

Dim scope As New ManagementScope("\\.\root\cimv2")
scope.Connect()

Dim objectQuery As New ObjectQuery("SELECT * FROM Win32_Processor")
Dim searcher As New ManagementObjectSearcher(scope, objectQuery)
Dim cpu As ManagementObject

For Each cpu In searcher.Get()
	Console.WriteLine("Processor: " & cpu["Name"])
	Console.WriteLine("Manufacturer: " & cpu["Manufacturer"])
	Console.WriteLine("Clock frequency: " & cpu["MaxClockSpeed"] & " MHz")
	Console.WriteLine("NumberOfLogicalProcessors: " & cpu["NumberOfLogicalProcessors"])
	Console.WriteLine("NumberOfCores: " & cpu["NumberOfCores"])
	Console.WriteLine()
Next cpu

However, obviously having Windows Vista as a requirement if your software is going to be spread is a bit harsh. :p

More info on the Win32_Processor WMI class.

If using P/Invoke, I only found GetLogicalProcessorInformation as an "easy" way out, but that requires Windows XP x64 or Vista too, so it's not much better as for the software requirements.

Edited June 26, 2007 by Jugalator

[scottb]

  azcodemonkey said:

That doesn't distinguish between CPUs and cores. AFAIK, you have to look at CPUID to determine if the reported CPUs are indeed cores on a chip or separate CPUs. With the ProcessorCount property, I'd hazard that it doesn't distinguish between cores or CPUs or HyperThreading.

I was curious to this myself, so i asked my m8 to test a simple app on his Dual Core system and it returned 2 and 1 on mine because i only have a P4. So it does look at cores? If you want to dig deep and get lots of information look at the System.Management namepsace in .NET.

[James Rose]

Thanks Jugalator, (great screen name btw)

Unfortunatly our CoLo, where our apps reside, is running Win2003.

[azcodemonkey]

  scottb said:

I was curious to this myself, so i asked my m8 to test a simple app on his Dual Core system and it returned 2 and 1 on mine because i only have a P4. So it does look at cores? If you want to dig deep and get lots of information look at the System.Management namepsace in .NET.

I just mean that you wouldn't be able to tell it was indeed 2 cores on 1 die, 2 separate cpus, or a hyperthreaded cpu.