GetThreadSelectedCpuSetMasks function (processthreadsapi.h)

Article
02/22/2024

Returns the explicit CPU Set assignment of the specified thread, if any assignment was set using SetThreadSelectedCpuSetMasks or SetThreadSelectedCpuSets.

Syntax

BOOL GetThreadSelectedCpuSetMasks(
  HANDLE          Thread,
  PGROUP_AFFINITY CpuSetMasks,
  USHORT          CpuSetMaskCount,
  PUSHORT         RequiredMaskCount
);

Parameters

Thread

Specifies the thread for which to query the selected CPU Sets. This handle must have the PROCESS_QUERY_LIMITED_INFORMATION access right. The value returned by GetCurrentProcess can also be specified here.

CpuSetMasks

Specifies an optional buffer to retrieve a list of GROUP_AFFINITY structures representing the thread selected CPU Sets.

CpuSetMaskCount

Specifies the size of the CpuSetMasks array, in elements.

RequiredMaskCount

On successful return, specifies the number of affinity structures written to the array. If the array is too small, the function fails with ERROR_INSUFFICIENT_BUFFER and sets the RequiredMaskCount parameter to the number of elements required. The number of required elements is always less than or equal to the maximum group count returned by GetMaximumProcessorGroupCount.

Return value

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero and extended error information can be retrieved by calling GetLastError.

If the array supplied is too small, the error value is ERROR_INSUFFICIENT_BUFFER and the RequiredMaskCount is set to the number of elements required.

Remarks

If no explicit assignment is set, RequiredMaskCount is set to 0 and the function succeeds.

This function is analogous to GetThreadSelectedCpuSets, except that it uses group affinities as opposed to CPU Set IDs to represent a list of CPU sets. This means that the thread selected CPU Sets are mapped to their home processors, and those processors are retrieved in the resulting list of group affinities.

Requirements

Requirement	Value
Minimum supported client	Windows 11
Minimum supported server	Windows Server 2022
Header	processthreadsapi.h
DLL	kernel32.dll

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