SYSTEM_CPU_SET_INFORMATION structure (winnt.h)

This structure is returned by GetSystemCpuSetInformation. It is used to enumerate the CPU Sets on the system and determine their current state.

This is a variable-sized structure designed for future expansion. When iterating over this structure, use the size field to determine the offset to the next structure.

Syntax

typedef struct _SYSTEM_CPU_SET_INFORMATION {
  DWORD                    Size;
  CPU_SET_INFORMATION_TYPE Type;
  union {
    struct {
      DWORD   Id;
      WORD    Group;
      BYTE    LogicalProcessorIndex;
      BYTE    CoreIndex;
      BYTE    LastLevelCacheIndex;
      BYTE    NumaNodeIndex;
      BYTE    EfficiencyClass;
      union {
        BYTE AllFlags;
        struct {
          BYTE Parked : 1;
          BYTE Allocated : 1;
          BYTE AllocatedToTargetProcess : 1;
          BYTE RealTime : 1;
          BYTE ReservedFlags : 4;
        } DUMMYSTRUCTNAME;
      } DUMMYUNIONNAME2;
      union {
        DWORD Reserved;
        BYTE  SchedulingClass;
      };
      DWORD64 AllocationTag;
    } CpuSet;
  } DUMMYUNIONNAME;
} SYSTEM_CPU_SET_INFORMATION, *PSYSTEM_CPU_SET_INFORMATION;

Members

Size

This is the size, in bytes, of this information structure.

Type

This is the type of information in the structure. Applications should skip any structures with unrecognized types.

DUMMYUNIONNAME

DUMMYUNIONNAME.CpuSet

DUMMYUNIONNAME.CpuSet.Id

The ID of the specified CPU Set. This identifier can be used with SetProcessDefaultCpuSets or SetThreadSelectedCpuSets when specifying a list of CPU Sets to affinitize to.

DUMMYUNIONNAME.CpuSet.Group

Specifies the Processor Group of the CPU Set. All other values in the CpuSet structure are relative to the processor group.

DUMMYUNIONNAME.CpuSet.LogicalProcessorIndex

Specifies the group-relative index of the home processor of the CPU Set. Unless the CPU Set is parked for thermal or power management reasons or assigned for exclusive use to another application, threads will run on the home processor of one of their CPU Sets. The Group and LogicalProcessorIndex fields are the same as the ones found in the PROCESSOR_NUMBER structure and they correspond to the Group field and Mask field of the GROUP_AFFINITY structure.

DUMMYUNIONNAME.CpuSet.CoreIndex

A group-relative value indicating which "Core" has the home processor of the CPU Set. This number is the same for all CPU Sets in the same group that share significant execution resources with each other, such as different hardware threads on a single core that supports simultaneous multi-threading.

DUMMYUNIONNAME.CpuSet.LastLevelCacheIndex

A group-relative value indicating which CPU Sets share at least one level of cache with each other. This value is the same for all CPU Sets in a group that are on processors that share cache with each other.

DUMMYUNIONNAME.CpuSet.NumaNodeIndex

A group-relative value indicating which NUMA node a CPU Set is on. All CPU Sets in a given group that are on the same NUMA node will have the same value for this field.

DUMMYUNIONNAME.CpuSet.EfficiencyClass

A value indicating the intrinsic energy efficiency of a processor for systems that support heterogeneous processors (such as ARM big.LITTLE systems). CPU Sets with higher numerical values of this field have home processors that are faster but less power-efficient than ones with lower values.

DUMMYUNIONNAME.CpuSet.DUMMYUNIONNAME2

DUMMYUNIONNAME.CpuSet.DUMMYUNIONNAME2.AllFlags

DUMMYUNIONNAME.CpuSet.DUMMYUNIONNAME2.DUMMYSTRUCTNAME

DUMMYUNIONNAME.CpuSet.DUMMYUNIONNAME2.DUMMYSTRUCTNAME.Parked

DUMMYUNIONNAME.CpuSet.DUMMYUNIONNAME2.DUMMYSTRUCTNAME.Allocated

DUMMYUNIONNAME.CpuSet.DUMMYUNIONNAME2.DUMMYSTRUCTNAME.AllocatedToTargetProcess

DUMMYUNIONNAME.CpuSet.DUMMYUNIONNAME2.DUMMYSTRUCTNAME.RealTime

DUMMYUNIONNAME.CpuSet.DUMMYUNIONNAME2.DUMMYSTRUCTNAME.ReservedFlags

DUMMYUNIONNAME.CpuSet.Reserved

Reserved.

DUMMYUNIONNAME.CpuSet.SchedulingClass

DUMMYUNIONNAME.CpuSet.AllocationTag

Specifies a tag used by Core Allocation to communicate a given allocated CPU Set between threads in different components.

Requirements

Requirement	Value
Minimum supported client	Windows 10 [desktop apps | UWP apps]
Minimum supported server	Windows Server 2016 [desktop apps | UWP apps]
Header	winnt.h (include Windows.h)