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Extract PMU profile source logic into reusable helpers #2188

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59267f2
Extract PMU profile source logic into reusable helpers
Arvean-microsoft Mar 11, 2026
9de1910
Clarify descriptions for PMU source information structures
Arvean-microsoft Mar 16, 2026
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180 changes: 178 additions & 2 deletions sdk-api-src/content/winternl/nf-winternl-ntquerysysteminformation.md
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UID: NF:winternl.NtQuerySystemInformation
title: NtQuerySystemInformation function (winternl.h)
description: Retrieves the specified system information.
helpviewer_keywords: ["NtQuerySystemInformation","NtQuerySystemInformation function","SYSTEM_BASIC_INFORMATION","SYSTEM_CODEINTEGRITY_INFORMATION","SYSTEM_EXCEPTION_INFORMATION","SYSTEM_INFORMATION_CLASS","SYSTEM_INTERRUPT_INFORMATION","SYSTEM_KERNEL_VA_SHADOW_INFORMATION","SYSTEM_LEAP_SECOND_INFORMATION","SYSTEM_LOOKASIDE_INFORMATION","SYSTEM_PERFORMANCE_INFORMATION","SYSTEM_POLICY_INFORMATION","SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION","SYSTEM_PROCESS_INFORMATION","SYSTEM_QUERY_PERFORMANCE_COUNTER_INFORMATION","SYSTEM_REGISTRY_QUOTA_INFORMATION","SYSTEM_SPECULATION_CONTROL_INFORMATION","SYSTEM_THREAD_INFORMATION","SYSTEM_TIMEOFDAY_INFORMATION","SYSTEM_VHD_BOOT_INFORMATION","SystemBasicInformation","SystemCodeIntegrityInformation","SystemExceptionInformation","SystemInterruptInformation","SystemKernelVaShadowInformation","SystemLeapSecondInformation","SystemLookasideInformation","SystemPerformanceInformation","SystemPolicyInformation","SystemProcessInformation","SystemProcessorPerformanceInformation","SystemQueryPerformanceCounterInformation","SystemRegistryQuotaInformation","SystemSpeculationControlInformation","SystemTimeOfDayInformation","base.ntquerysysteminformation","winternl/NtQuerySystemInformation"]
helpviewer_keywords: ["NtQuerySystemInformation","NtQuerySystemInformation function","SYSTEM_BASIC_INFORMATION","SYSTEM_CODEINTEGRITY_INFORMATION","SYSTEM_EXCEPTION_INFORMATION","SYSTEM_INFORMATION_CLASS","SYSTEM_INTERRUPT_INFORMATION","SYSTEM_KERNEL_VA_SHADOW_INFORMATION","SYSTEM_LEAP_SECOND_INFORMATION","SYSTEM_LOOKASIDE_INFORMATION","SYSTEM_PERFORMANCE_INFORMATION","SYSTEM_PMU_SOURCE_ADD_INFORMATION","SYSTEM_PMU_SOURCE_REMOVE_INFORMATION","SYSTEM_POLICY_INFORMATION","SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION","SYSTEM_PROCESS_INFORMATION","SYSTEM_QUERY_PERFORMANCE_COUNTER_INFORMATION","SYSTEM_REGISTRY_QUOTA_INFORMATION","SYSTEM_SPECULATION_CONTROL_INFORMATION","SYSTEM_THREAD_INFORMATION","SYSTEM_TIMEOFDAY_INFORMATION","SYSTEM_VHD_BOOT_INFORMATION","SystemBasicInformation","SystemCodeIntegrityInformation","SystemExceptionInformation","SystemInterruptInformation","SystemKernelVaShadowInformation","SystemLeapSecondInformation","SystemLookasideInformation","SystemPerformanceInformation","SystemPmuSourceAddInformation","SystemPmuSourceRemoveInformation","SystemPolicyInformation","SystemProcessInformation","SystemProcessorPerformanceInformation","SystemQueryPerformanceCounterInformation","SystemRegistryQuotaInformation","SystemSpeculationControlInformation","SystemTimeOfDayInformation","base.ntquerysysteminformation","winternl/NtQuerySystemInformation"]
old-location: base\ntquerysysteminformation.htm
tech.root: winprog
ms.assetid: 553ec7b9-c5eb-4955-8dc0-f1c06f59fe31
ms.date: 12/05/2018
ms.keywords: NtQuerySystemInformation, NtQuerySystemInformation function, SYSTEM_BASIC_INFORMATION, SYSTEM_CODEINTEGRITY_INFORMATION, SYSTEM_EXCEPTION_INFORMATION, SYSTEM_INFORMATION_CLASS, SYSTEM_INTERRUPT_INFORMATION, SYSTEM_KERNEL_VA_SHADOW_INFORMATION, SYSTEM_LEAP_SECOND_INFORMATION, SYSTEM_LOOKASIDE_INFORMATION, SYSTEM_PERFORMANCE_INFORMATION, SYSTEM_POLICY_INFORMATION, SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION, SYSTEM_PROCESS_INFORMATION, SYSTEM_QUERY_PERFORMANCE_COUNTER_INFORMATION, SYSTEM_REGISTRY_QUOTA_INFORMATION, SYSTEM_SPECULATION_CONTROL_INFORMATION, SYSTEM_THREAD_INFORMATION, SYSTEM_TIMEOFDAY_INFORMATION, SYSTEM_VHD_BOOT_INFORMATION, SystemBasicInformation, SystemCodeIntegrityInformation, SystemExceptionInformation, SystemInterruptInformation, SystemKernelVaShadowInformation, SystemLeapSecondInformation, SystemLookasideInformation, SystemPerformanceInformation, SystemPolicyInformation, SystemProcessInformation, SystemProcessorPerformanceInformation, SystemQueryPerformanceCounterInformation, SystemRegistryQuotaInformation, SystemSpeculationControlInformation, SystemTimeOfDayInformation, base.ntquerysysteminformation, winternl/NtQuerySystemInformation
ms.keywords: NtQuerySystemInformation, NtQuerySystemInformation function, SYSTEM_BASIC_INFORMATION, SYSTEM_CODEINTEGRITY_INFORMATION, SYSTEM_EXCEPTION_INFORMATION, SYSTEM_INFORMATION_CLASS, SYSTEM_INTERRUPT_INFORMATION, SYSTEM_KERNEL_VA_SHADOW_INFORMATION, SYSTEM_LEAP_SECOND_INFORMATION, SYSTEM_LOOKASIDE_INFORMATION, SYSTEM_PERFORMANCE_INFORMATION, SYSTEM_PMU_SOURCE_ADD_INFORMATION, SYSTEM_PMU_SOURCE_REMOVE_INFORMATION, SYSTEM_POLICY_INFORMATION, SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION, SYSTEM_PROCESS_INFORMATION, SYSTEM_QUERY_PERFORMANCE_COUNTER_INFORMATION, SYSTEM_REGISTRY_QUOTA_INFORMATION, SYSTEM_SPECULATION_CONTROL_INFORMATION, SYSTEM_THREAD_INFORMATION, SYSTEM_TIMEOFDAY_INFORMATION, SYSTEM_VHD_BOOT_INFORMATION, SystemBasicInformation, SystemCodeIntegrityInformation, SystemExceptionInformation, SystemInterruptInformation, SystemKernelVaShadowInformation, SystemLeapSecondInformation, SystemLookasideInformation, SystemPerformanceInformation, SystemPmuSourceAddInformation, SystemPmuSourceRemoveInformation, SystemPolicyInformation, SystemProcessInformation, SystemProcessorPerformanceInformation, SystemQueryPerformanceCounterInformation, SystemRegistryQuotaInformation, SystemSpeculationControlInformation, SystemTimeOfDayInformation, base.ntquerysysteminformation, winternl/NtQuerySystemInformation
req.header: winternl.h
req.include-header:
req.target-type: Windows
Expand Down Expand Up @@ -120,6 +120,18 @@ used to generate an unpredictable seed for a random number generator. Use the



#### SystemPmuSourceAddInformation

Accepts a <b>SYSTEM_PMU_SOURCE_ADD_INFORMATION</b> structure that describes a PMU (Performance Monitoring Unit) profile source to add.



#### SystemPmuSourceRemoveInformation

Accepts a <b>SYSTEM_PMU_SOURCE_REMOVE_INFORMATION</b> structure that identifies a PMU (Performance Monitoring Unit) profile source to remove.



#### SystemPolicyInformation

Returns policy information in a <b>SYSTEM_POLICY_INFORMATION</b> structure. Use the <a href="/windows/desktop/api/slpublic/nf-slpublic-slgetwindowsinformation">SLGetWindowsInformation</a> function instead to obtain policy information.
Expand Down Expand Up @@ -662,6 +674,170 @@ function instead to generate cryptographically random data.



#### SYSTEM_PMU_SOURCE_ADD_INFORMATION

When the <i>SystemInformationClass</i> parameter is
<b>SystemPmuSourceAddInformation</b>, the buffer pointed to by
the <i>SystemInformation</i> parameter should be large enough
to hold a single <b>SYSTEM_PMU_SOURCE_ADD_INFORMATION</b> structure
having the following layout:



``` syntax
typedef struct _SYSTEM_PMU_SOURCE_ADD_INFORMATION {
union {
struct {
UCHAR PerfEvtEventSelect;
UCHAR PerfEvtUnitSelect;
UCHAR PerfEvtCMask;
UCHAR PerfEvtCInv;
UCHAR PerfEvtAnyThread;
UCHAR PerfEvtEdgeDetect;
} Intel;
struct {
USHORT PerfEvtEventSelect;
UCHAR PerfEvtUnitSelect;
UCHAR PerfEvtCMask;
UCHAR PerfEvtCInv;
UCHAR PerfEvtEdgeDetect;
UCHAR PerfEvtHostGuest;
UCHAR PerfPmuType;
} Amd;
struct {
ULONG PerfEvtType;
BOOLEAN AllowsHalt;
} Arm;
};
ULONG CpuInfoHierarchy[3];
ULONG InitialInterval;
BOOLEAN Persist;
WCHAR ProfileSourceDescription[ANYSIZE_ARRAY];
} SYSTEM_PMU_SOURCE_ADD_INFORMATION, *PSYSTEM_PMU_SOURCE_ADD_INFORMATION;
```

The architecture-specific union at the start of the structure contains the PMC (Performance Monitoring Counter) event configuration. The appropriate union member is selected based on the processor architecture.

The <b>Intel</b> member is used on Intel processors and contains the following fields:

<table>
<tr>
<td><b>Field</b></td>
<td><b>Meaning</b></td>
</tr>
<tr>
<td>PerfEvtEventSelect</td>
<td>The PMC event select value.</td>
</tr>
<tr>
<td>PerfEvtUnitSelect</td>
<td>The PMC logical unit select value.</td>
</tr>
<tr>
<td>PerfEvtCMask</td>
<td>An optional non-zero counter mask.</td>
</tr>
<tr>
<td>PerfEvtCInv</td>
<td>An optional counter mask invert bit.</td>
</tr>
<tr>
<td>PerfEvtAnyThread</td>
<td>An optional AnyThread bit.</td>
</tr>
<tr>
<td>PerfEvtEdgeDetect</td>
<td>An optional edge detection bit.</td>
</tr>
</table>

The <b>Amd</b> member is used on AMD processors and contains the following fields:

<table>
<tr>
<td><b>Field</b></td>
<td><b>Meaning</b></td>
</tr>
<tr>
<td>PerfEvtEventSelect</td>
<td>The PMC event select value.</td>
</tr>
<tr>
<td>PerfEvtUnitSelect</td>
<td>The PMC logical unit select value.</td>
</tr>
<tr>
<td>PerfEvtCMask</td>
<td>An optional non-zero counter mask.</td>
</tr>
<tr>
<td>PerfEvtCInv</td>
<td>An optional counter mask invert bit.</td>
</tr>
<tr>
<td>PerfEvtEdgeDetect</td>
<td>An optional edge detection bit.</td>
</tr>
<tr>
<td>PerfEvtHostGuest</td>
<td>An optional host/guest only bit.</td>
</tr>
<tr>
<td>PerfPmuType</td>
<td>An optional PMU type of the event.</td>
</tr>
</table>

The <b>Arm</b> member is used on ARM processors and contains the following fields:

<table>
<tr>
<td><b>Field</b></td>
<td><b>Meaning</b></td>
</tr>
<tr>
<td>PerfEvtType</td>
<td>The PMC event type.</td>
</tr>
<tr>
<td>AllowsHalt</td>
<td>Toggles profiling across halt states.</td>
</tr>
</table>

The <b>CpuInfoHierarchy</b> member is an array of three ULONG values that identify the target processor microarchitecture. For x86/x64/AMD64 processors, the values represent Family, Model, and Stepping. For ARM/ARM64 processors, the values represent Vendor, Model, and Revision. A value of -1 indicates "Not Specified".

The <b>InitialInterval</b> member contains the initial sampling interval for the profile source.

The <b>Persist</b> member indicates whether the profile source should persist across reboots by saving the configuration to the registry.

The <b>ProfileSourceDescription</b> member contains a variable-length null-terminated Unicode string that provides a human-readable description of the profile source.



#### SYSTEM_PMU_SOURCE_REMOVE_INFORMATION

When the <i>SystemInformationClass</i> parameter is
<b>SystemPmuSourceRemoveInformation</b>, the buffer pointed to by
the <i>SystemInformation</i> parameter should be large enough
to hold a single <b>SYSTEM_PMU_SOURCE_REMOVE_INFORMATION</b> structure
having the following layout:



``` syntax
typedef struct _SYSTEM_PMU_SOURCE_REMOVE_INFORMATION {
ULONG ProfileSource;
ULONG CpuInfoHierarchy[3];
} SYSTEM_PMU_SOURCE_REMOVE_INFORMATION, *PSYSTEM_PMU_SOURCE_REMOVE_INFORMATION;
```

The <b>ProfileSource</b> member identifies the profile source to remove.

The <b>CpuInfoHierarchy</b> member is an array of three ULONG values that identify the target processor microarchitecture. For x86/x64/AMD64 processors, the values represent Family, Model, and Stepping. For ARM/ARM64 processors, the values represent Vendor, Model, and Revision. A value of -1 indicates "Not Specified".



#### SYSTEM_POLICY_INFORMATION

When the <i>SystemInformationClass</i> parameter is
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