How to explicitly assign a thread to a core of the processor?

[NaOHwwl]

Greetings, everyone!

I have a question, maybe simple and stupid since I've never touched this area before.

I have a 64-bit laptop with Windows 7 Professional and a 8-core CPU. I use Visual Studio 2012 Express to build my program.

I am coding a project which is highly required at the speed performance, thus I need everything I can grab to speed it up. What I want to achieve is to explicitly assign my threads to each of the CPU cores.

Therefore, I have few questions as follows:

1. Is it necessary to explicitly assign threads to cores?

2. I know Windows has a well designed method to automatically allocate the threads to the CPU cores. But what I don't know is if this is efficient? Because sometimes I monitor the CPU usage, I find it usually in idle status even I am running something.

3. If, for a specific task, explicitly allocate threads to the cores is more efficient than leave it to the operating system. How to achieve so? Is there any examples or code clips that I can learn from?

Thank you very much in advacne. I would extremely appreciate if you can bring me some ideas.

Regards
Long

[modoran]

You should read this:
http://msdn.microsoft.com/en-us/library/ms685100%28VS.85%29.aspx

[andywestken]

I can't answer your specific questions, but...

My inderstanding is that Windows thread scheduling in good for general purposes, but I have come across customing scheduling code for special purposes. But this is something I'd only expect to see on a dedicated server.

As well as adjusting the thread priority, as the article mordoran pointed you at shows, you can control where your threads runs using SetThreadAffinityMask

SetThreadAffinityMask function
http://msdn.microsoft.com/en-us/library/windows/desktop/ms686247%28v=vs.85%29.aspx

BUT this function is seen as rather problematic, even dangerous, when mis-used.

You mention tasks in your final point which, together with you general question, suggests you might be interested in Microsoft PPL (Parallel Patterns Library) or Intel TBB (Threading Building Blocks). I don't know a lot about these yet, but am currently trying to learn more about them.

In the end, I think that trying trying to explicitly allocate threads to the cores would probably be rather tricky. But these new task-based approaches might be able to help.

Andy

Parallel Patterns Library (PPL)
http://msdn.microsoft.com/en-us/library/dd492418.aspx

Threading Building Blocks
http://threadingbuildingblocks.org/