Number of hardware processors (cores)

[John E]

Hi guys. This is way out of my league but I thought someone here might have some ideas...

Apparently there are various methods (GetSystemInfo() / GetLogicalProcessorInfoEx() etc) which can return the number of available processors. But they usually return the number of logical processors and they're affected by stuff like hyperthreading. So for example, depending on how you get the information, a dual-core CPU can either return 1, 2 or 4 processors.

I've been asked if there's any simple way to retrieve the actual number of physical processor cores - i.e. such that a dual core CPU will always get returned as '2'. An 8-core CPU would return '8' etc. Any ideas anyone?

[Codeplug]

http://msdn.microsoft.com/en-us/libr...(v=vs.85).aspx

There is sample code there that seems to extract that info.

gg

[zerver]

IIRC, if you want a solution that works on as many versions of windows as possible, you have to resort to assembly hacks. I may have some example code if you are interested.

[Arjay]

You can also use WMI.

[OReubens]

what's the difference betwee 1 dual core processor and 2 single core processors ?
other than the physical packaging, they'll behave identically as far as an OS is concerned.

wanting to know if a core is a hyperthreading or a real core, ok I can see reasons why you'd want to know why it is either, because the hyperthreaded cores are slightly less capable as their real counterpart.

[zizz]

Any ideas anyone?

You can get that information from a package that's designed to utilize multiple cores.

This will allow you not only to know how many cores you have at your disposal but also to utilize the cores optimally in your programs.

My favourite is TBB from Intel.

[OReubens]

Tbh. Why do you even need this ?
Most cases I've seen where devs tried to "game" the system trying to get more oomph out of the system, they ended up doing the opposite, or they ended up getting more speed, but at the cost of making the entire rest of the PC unusable for anything meanwhile.

Doing massively multithreading properly is hard... very hard... more ofen than not you see software that spends a large amount of it's time in the waiting loops trying to sync up.

[zizz]

Tbh. Why do you even need this ?

Do you mean TBB and replied to me?

[2kaud]

I've been asked if there's any simple way to retrieve the actual number of physical processor cores - i.e. such that a dual core CPU will always get returned as '2'. An 8-core CPU would return '8' etc

but for what is this data going to be used? Just for info purposes or??

[John E]

Thanks guys. Shortly after posting I came down with some horrible virus (i.e. dizziness / cold / headache etc - not a computer virus!) but there's plenty of stuff here for me to investigate once I'm feeling a bit better. Thanks!