C# Threading Parked CPU's?

Question

System.Environment.ProcessorCount shows me N Processors (N in my case = 8), which I want to make use of. Now the problem is, that the windows resourcemanager sais, that 4 of my CPU's are 'parked', and the 8 Threads i start just seperate up to the 4 unblocked CPUs.

Now is there a way to use the parked CPU's, too?

Answer 1

When Windows "parks" a CPU core, it means that there is not enough work for that core to do so it puts that core in a low-power state. In order to "unpark" the CPU, you just have to create enough work.

If you are starting 8 threads and Windows isn't unparking the CPUs, the threads probably are doing I/O, blocking, or completing too quickly. If you post what your threads are doing, maybe somebody can explain why they're not running on the parked cores.

Answer 2

Usually, you should be able to do it this way:

Process.GetCurrentProcess().ProcessorAffinity = (IntPtr)0x00FF;

see documentation for it here:
http://msdn.microsoft.com/en-us/library/system.diagnostics.process.processoraffinity.aspx

but it also says that, by default your process is assigned to all cores.

On the other hand, you could try ProcessThread.ProcessorAffinity and try to set it manually (if you want to force each thread to use another core).