Windows Server / Datacenter：将CPU关联设置为> 64个核心

Question

SetThreadAffinityMask() allows one to set an affinity mask for 64 logical cores (processors). However, Windows Datacenter can have up to 64 CPUs, each with many cores (see here ).

How does one set threads for > 64 cores?

Ps. I am coding in C#, so a .Net answer is ideal, but an API one in C is fine too.

Answer 1

According to MSDN, SetThreadAffinityMask() sets the affinity for your current processor group, each of which can have 64 logical cores each. Change your group with SetThreadGroupAffinity(). See http://msdn.microsoft.com/en-us/library/windows/desktop/dd405503(v=vs.85).aspx for more.

Answer 2

I use the following code to set the affinity for processor groups and CPUs:

[StructLayout(LayoutKind.Sequential, Pack = 4)]
private struct _GROUP_AFFINITY
{
    public UIntPtr Mask;
    [MarshalAs(UnmanagedType.U2)]
    public ushort Group;
    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 3, ArraySubType = UnmanagedType.U2)]
    public ushort[] Reserved;
}

[DllImport("kernel32", SetLastError = true)]
private static extern Boolean SetThreadGroupAffinity(
    IntPtr hThread,
    ref _GROUP_AFFINITY GroupAffinity,
    ref _GROUP_AFFINITY PreviousGroupAffinity);

[DllImport("kernel32", SetLastError = true)]
private static extern IntPtr GetCurrentThread();

/// <summary>
/// Sets the processor group and the processor cpu affinity of the current thread.
/// </summary>
/// <param name="group">A processor group number.</param>
/// <param name="cpus">A list of CPU numbers. The values should be
/// between 0 and <see cref="Environment.ProcessorCount"/>.</param>
public static void SetThreadProcessorAffinity(ushort groupId, params int[] cpus)
{
    if (cpus == null) throw new ArgumentNullException(nameof(cpus));
    if (cpus.Length == 0) throw new ArgumentException("You must specify at least one CPU.", nameof(cpus));

    // Supports up to 64 processors
    long cpuMask = 0;
    foreach (var cpu in cpus)
    {
        if (cpu < 0 || cpu >= Environment.ProcessorCount)
            throw new ArgumentException("Invalid CPU number.");

        cpuMask |= 1L << cpu;
    }

    var hThread = GetCurrentThread();
    var previousAffinity = new _GROUP_AFFINITY {Reserved = new ushort[3]};
    var newAffinity = new _GROUP_AFFINITY
    {
        Group = groupId,
        Mask = new UIntPtr((ulong) cpuMask),
        Reserved = new ushort[3]
    };

    SetThreadGroupAffinity(hThread, ref newAffinity, ref previousAffinity);
}

Answer 3

In order to work with more than 64 CPUs, you have to take processor groups into account. Refer to MSDN for details:

Processor Groups