GetProcessDefaultCpuSetMasks function (processthreadsapi.h)

Article
01/27/2022

Retrieves the list of CPU Sets in the process default set that was set by SetProcessDefaultCpuSetMasks or SetProcessDefaultCpuSets.

Syntax

BOOL GetProcessDefaultCpuSetMasks(
  HANDLE          Process,
  PGROUP_AFFINITY CpuSetMasks,
  USHORT          CpuSetMaskCount,
  PUSHORT         RequiredMaskCount
);

Parameters

Process

Specifies a process handle for the process to query. 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 process default 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 CpuSetMasks 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 default CPU Sets are set for a given process, then the RequiredMaskCount parameter is set to 0 and the function succeeds.

This function is analogous to GetProcessDefaultCpuSets, except that it uses group affinities as opposed to CPU Set IDs to represent a list of CPU sets. This means that the process default 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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