GetProcessAffinityMask

Overview

Retrieves the process affinity mask for the specified process and the system affinity mask for the system on which the process is running.

Syntax

BOOL GetProcessAffinityMask(
    HANDLE     hProcess,
    PDWORD_PTR lpProcessAffinityMask,
    PDWORD_PTR lpSystemAffinityMask
);

Parameters

Name	Type	Description
hProcess	HANDLE	Handle to the process whose affinity mask is to be retrieved. The handle must have PROCESS_QUERY_INFORMATION access.
lpProcessAffinityMask	PDWORD_PTR	Pointer to a variable that receives the process affinity mask.
lpSystemAffinityMask	PDWORD_PTR	Pointer to a variable that receives the system affinity mask.

Return Value

If the function succeeds, the return value is nonzero. If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

The process affinity mask is a bitmask in which each bit represents a logical processor that the process is allowed to run on.
The system affinity mask indicates the processors that are configured into the system.
Use SetProcessAffinityMask to change a process's affinity mask.
On systems with more than 64 logical processors, the affinity mask is represented as a DWORD_PTR array.

Example

#include <windows.h>
#include <stdio.h>

int main(void)
{
    HANDLE hProcess = GetCurrentProcess();
    DWORD_PTR processMask, systemMask;

    if (GetProcessAffinityMask(hProcess, &processMask, &systemMask))
    {
        printf("Process Affinity Mask: 0x%I64x\n", (unsigned long long)processMask);
        printf("System Affinity Mask : 0x%I64x\n", (unsigned long long)systemMask);
    }
    else
    {
        printf("GetProcessAffinityMask failed. Error: %lu\\n", GetLastError());
    }
    return 0;
}