In C# can I specify a preferred core number for a thread to be executed?

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In C# can I specify a preferred core number for a thread to be executed?
Example:- if there are two threads and the PC has two cores. Do I have the option of specifying, Thread one execute on core one and Thread two execute on core two?

Posted 23-Mar-11 4:50am

Panchaz

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3 solutions

Solution 3

You can use System.Threading.Thread.BeginThreadAffinity/EndThreadAffinity, for compact Framework — System.Threading.Thread.SetProcessorAffinity.

Use with care, it can potentially do more harm than help. I would only use to serve some specific hardware which require polling, for example.

—SA

Posted 23-Mar-11 14:25pm

Sergey Alexandrovich Kryukov

Comments

Rick Shaub 23-Mar-11 20:35pm

I don't think this is a Compact Framework question.

Sergey Alexandrovich Kryukov 23-Mar-11 21:02pm

This is mentioned only for completeness, only for the last API; what's wrong about it?
Pay attention for my punctuation... Nothing wrong, I guess??
--SA

Rick Shaub 24-Mar-11 10:35am

BeginThreadAffinity/EndThreadAffinity don't do the same thing as the OP asked.

Sergey Alexandrovich Kryukov 24-Mar-11 12:04pm

I wonder why.
--SA

Panchaz 23-Mar-11 23:03pm

This is not a .NET Compact Framework problem. :(

Sergey Alexandrovich Kryukov 23-Mar-11 23:07pm

Should I repeat what I just said?!!!!!
My Answer in NOT (!!!) about Compact framework. ONLY a part "System.Threading.Thread.SetProcessorAffinity" is about Compact, everything else about regular Framework.
--SA

Espen Harlinn 24-Mar-11 4:04am

Good reply - BeginThreadAffinity/EndThreadAffinity (on regular .Net) usually improves the performance computationally intensive threads significantly.

Sergey Alexandrovich Kryukov 24-Mar-11 4:28am

I would say, in special cases, after thorough design. In regular application better not touching it.
Thank you.
--SA

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Rick Shaub · Accepted Answer · 2011-03-23T05:03:00

Solution 2

You can using p/invoke.
First you want to create a thread using the CreateThread[^]function.
Then, pass the return value from CreateThread to SetThreadIdealProcessor[^]

Posted 23-Mar-11 5:03am

Rick Shaub

Comments

Panchaz 23-Mar-11 11:12am

can i do this on 64bit platform?

Rick Shaub 23-Mar-11 11:23am

It should work especially if you are compiling on a 64 bit system. It looks like stack alignment can be troublesome in some cases see http://stackoverflow.com/questions/3046439/createthread-fails-on-64-bit-windows-works-on-32-bit-windows-why and http://msdn.microsoft.com/en-us/library/aa290049%28VS.71%29.aspx

Sergey Alexandrovich Kryukov 23-Mar-11 20:26pm

I don't think it needs P/Invoke. This is a matter of thread affinity; please see my Answer.
(I did not vote.)
--SA

#realJSOP · Accepted Answer · 2011-03-23T04:57:00

Solution 1

Yes, but you're wasting your time. Windows/.Net assigns core affinity for threads and processes automagically.

EDIT ========

1-voting this isn't going to change the truth of what I say.

Posted 23-Mar-11 4:57am

#realJSOP

Updated 23-Mar-11 6:29am

v2

Comments

Panchaz 23-Mar-11 10:59am

i know but this is a requirement

#realJSOP 23-Mar-11 11:27am

What if the core number you want to use isn't implemented on the system your app is on? The "requirement" is artificial and arbitrary given .Net's ability to handle this for you.

Dave Kreskowiak 24-Mar-11 0:03am

It's a stupid requirement. What if the core is tied up with other threads, but there's an available core that isn't doing anything? Your code has to wait. You're actually sacrificing performance, not gaining it.

Rick Shaub 23-Mar-11 12:55pm

FYI- I agree that in most cases it's a waste of time. I just answered his question. I also didn't 1 vote you.

#realJSOP 23-Mar-11 21:14pm

I know - that 1-vote comment was for everyone. :)

Espen Harlinn 24-Mar-11 4:12am

I'm not downvoting you, but:
BeginThreadAffinity/EndThreadAffinity (on regular .Net) usually improves the performance computationally intensive threads - so if the computer is dedicated to the execution of some parallelized heavy calculation, it makes sense to do this. Appearantly that automagic doesn't work as well as one would have liked, because I've experienced more than 20% improvement in execution time, something that was quite useful at the time :)