In Windows, when you have more than 64 logical processors, the system groups them into processor groups. Each group can have a maximum of 64 processors. Unfortunately, the .NET `System.Diagnostics.Process` class does not directly support setting processor affinity across multiple processor groups.
However, you can use P/Invoke to call Windows API functions to set processor affinity across different processor groups. Here's an example of how you can do this in C#:
using System;
using System.Diagnostics;
using System.Runtime.InteropServices;
class Program
{
[StructLayout(LayoutKind.Sequential)]
struct GROUP_AFFINITY
{
public UIntPtr Mask;
public ushort Group;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 3)]
public ushort[] Reserved;
}
[DllImport("kernel32.dll", SetLastError = true)]
static extern bool SetThreadGroupAffinity(IntPtr hThread, ref GROUP_AFFINITY GroupAffinity, IntPtr PreviousGroupAffinity);
[DllImport("kernel32.dll", SetLastError = true)]
static extern IntPtr OpenThread(uint dwDesiredAccess, bool bInheritHandle, uint dwThreadId);
[DllImport("kernel32.dll", SetLastError = true)]
static extern bool CloseHandle(IntPtr hObject);
const uint THREAD_SET_INFORMATION = 0x0020;
static void Main(string[] args)
{
int myProcessId = 1234; // Replace with your process ID
Process process = Process.GetProcessById(myProcessId);
foreach (ProcessThread thread in process.Threads)
{
IntPtr hThread = OpenThread(THREAD_SET_INFORMATION, false, (uint)thread.Id);
if (hThread == IntPtr.Zero)
{
Console.WriteLine($"Failed to open thread {thread.Id}");
continue;
}
GROUP_AFFINITY groupAffinity = new GROUP_AFFINITY
{
Mask = (UIntPtr)0xFFFFFFFF, // Set the mask to use all CPUs in the group, adjust as needed
Group = 0, // Set to the desired processor group
Reserved = new ushort[3]
};
if (!SetThreadGroupAffinity(hThread, ref groupAffinity, IntPtr.Zero))
{
Console.WriteLine($"Failed to set thread group affinity for thread {thread.Id}");
}
CloseHandle(hThread);
}
}
}
In this example, you need to replace `myProcessId` with your actual process ID. This code sets the affinity for each thread in the process to use all CPUs in group 0. You can adjust the `Mask` and `Group` fields of the `GROUP_AFFINITY` structure as needed.
Note that this example only sets the affinity for one processor group. Setting affinity across multiple groups for a single process is more complex and might not be supported directly. You would need to ensure that threads are distributed across groups as needed.
I hope this helps.
